ENVIRONMENTAL AIR POLLUTION

IIT(M) LECTURE NOTES

History of Air Pollution 1272 - King Edward I of England bans use of “sea coal”

1377 – 1399 - Richard II restricts use of coal

1413 – 1422 - Henry V regulates/restricts use of coal

1661 - By royal command of Charles II, John Evelyn of the Royal Society publishes “Fumifugium; or the Inconvenience of the Air and Smoke dissipated; together with Some Remedies Humbly Proposed”

1784—Watt’s steam engine; boilers to burn fossil fuels (coal) to make steam to pump water and move machinery

Smoke and ash from fossil fuels by power plants, trains, ships: coal (and oil) burning = smoke, ash

1907 - Formation of the predecessor to the Air & Waste Management Association

1930 - 1950’s - Air Pollution Episodes

1955 First Federal Air Pollution Control Act - funds for research (USA)

1960 Motor Vehicle Exhaust Act - funds for research (USA)

1963 Clean Air Act (USA)-Three stage enforcement-Funds for state and local agencies

1965 Motor Vehicle Air Pollution Control Act (USA)-Emission regulations for cars to begin in 1968

1967 Air Quality Act (USA)-Criteria documents-Control technique documents

1970 Clean Air Act Amendments (USA)-National Ambient Air Quality Standards-New Source Performance Standards

Why study air pollution ?

Early 1900s The City of Chicago, Illinois passes an ordinance to reduce the “smoke” emitted by local factories.

1940s Los Angeles, California becomes one of the first cities in the U.S. to experience severe air pollution problems then called “gas attacks.” L.A.’s location in a basin like area ringed by mountains makes it susceptible to accumulation of auto exhaust and emissions from local petroleum refineries

1948 Air pollution kills in Donora, Pennsylvania. An unusual temperature inversion lasting six days blocks dispersal of emissions from zinc smelting and blast furnaces. Out of a total population of 14,000 people, 20 die, 600 others become ill, and 1400 seek medical attention.

1950 A chemist at the California Institute of Technology proposes a theory of smog (or ozone) formation in which auto exhaust and sunlight play major roles.

1954 An early public protest against air pollution takes place in East Greenville, Pennsylvania. Homemakers march on the town council to demand that a local casket manufacturer be required to stop polluting. Their complaint is that clean laundry hung out to dry became dirtier than before it was washed because of high levels of soot (or particulates) in the air.

1962 Silent Spring is published. Rachel Carson’s powerful book draws the attention of the American public

to the potential consequences of the increasing ability of human activities to significantly and even permanently alters the natural world.

1966 In New York City, a three-day temperature inversion over Thanksgiving weekend is blamed for the deaths of 168 people.

1969 Millions of Americans watch via satellite, as Neil Armstrong becomes the first person to walk on the moon. The same weekend, a very different news story startles the nation. Sulfur dioxide pollution emitted by industries near Gary, Indiana and East Chicago becomes potent acid rain that burns lawns, eats away tree leaves, and causes birds to lose their feathers.

1969 A vivid color photographs of Earth from space, widely distributed, shifts human perceptions of our planet. The Earth no longer seems vast but is recognized as a small, fragile ball of life in the immense infinitude of cold, black space.

1970 The first Earth Day becomes part of American history. Millions of students and citizens attend rallies to learn about environmental concerns and speak for environmental protection.

1972 Representatives of 113 nations, gather on 5th June at a United Nations Conference on the Human Environment in Stockholm to develop plans for international action to protect the world environment.

1978 Rainfall in Wheeling, West Virginia is measured at a pH of 2, the most acidic yet recorded and 5000 times more acidic than normal rainfall.

1981 Air pollution enters international politics when the Quebec Ministry of the Environment notifies the U.S. that 60 percent of the acid rain (sulfur dioxide pollution) damaging air and waters in Quebec, Canada comes from the U.S. industrial sources in the Midwestern and Northeastern U.S.

1982 The National Center for Health Statistics releases a study indicating that four percent of all U.S. schoolchildren, including about 12 percent of all African-American preschoolers, have high levels of lead in their blood. About 675,000 children are at risk of kidney damage, brain damage, anemia, retardation, and other ills associated with lead poisoning. It is recognized that children absorb this lead by breathing air laden with lead pollution, primarily from leaded gasoline.

1985 The U.S. EPA estimates 50,000 streams in the U.S. and Canada are dead or dying because of acid rain pollution.

1986 The National Academy of Sciences reports that the burning of coal, gasoline, and other fossil fuels is definitely linked to acid rain and the death of trees, fish, and lake ecosystems in both the U.S. and Canada.

1992 The Earth Summit in Rio de Janeiro, Brazil is the most comprehensive international conference on the environment to date. Representatives from 188 countries and 35,000 participants attend. Two treaties are signed by all except the U.S. One, on global warming recommending curbing emissions of greenhouse gases. The second, on making inventories of plants and wildlife and strategies to protect endangered species.

 

Air Pollution Episodes Period of poor air qulaity, upto several days, often extending over large geograpical area.

Winter: cold, stable weather conditions trap pollutants close to sources and prevent dispersion. Elavated concentrations of range of pollutants build up over several days

Summer: hot and sunny weather. Pollutants emitted within the U.K. or Europe transported long distances, reacting with each other in sunlight to produce high levels of ozone, & other photochemical pollutants.

Meuse Valley-Belgium, 1930

63 died (mostly elderly)

Sore throats, shortness of breath, cough, phlegm, nausea, vomiting

SO2, sulfur dioxide

H2O

SO4 sulfuric acid mist

Cattle, birds and rats died

Got little news coverage

 

Fumigation of a valley floor caused by an inversion layer that restricts diffusion from a stack

Donora, Pennsylvania—Oct. 1948

Monongahela River Valley

Industrial town—steel mill, sulfuric acid plant, freight yard, etc.

Population—14,000

Steep hills surrounding the valley

Oct 26—temperature inversion (warm air trapping cold air near the ground)

Stable air, fog, lasted 4.5 days

Environs of Donora, Pennsylvania. Horseshoe curve of Monongahela River is surrounded by mountains. Railroad tracks are located on both sides of the river. Low-lying stretch of Monongahela valley between railroad and river is natural trap for pollutants.

Poza Rico, Mexico 1950

Single source– high sulfur crude oil Hydrogen sulfide (H2S)

Flare went out

Inversion in valley

22 sudden deaths, 320 hospitalized All ages

Forerunner of Bhopal

December 1952 Great London Smog

Cold front, Londoners burned soft coal Factories, power plants

Temperature inversion

5 days of worst smog city had ever seen Public transportation stopped

Indoor concerts had to be cancelled because no one could see the stage, etc.

 

Weekly death registered from diseases of the lungs and heart in the London Administrative County around the time of the severe fog in December, 1952.

Total death in Greater London and air pollutants levels measured during the fog of December 1952

Seveso, Italy --Dioxin

July 10, 1976, north of Milan A valve broke at the Industrie Chimiche Meda Societa Azionaria chemical plant

Cloud of 2,3,7,8 tetrachlorodibenzo-para-dioxin (TCDD) traveled southwest through Seveso toward Milan

Contaminant of herbicide

Bhopal, India Dec. 3, 1984

Union Carbide pesticide plant leak kills up to 2,000 with up to 350,000 injured and 100,000 with permanent disabilities

Methyl isocyanate (MIC)—used as an intermediary in manufacture of Sevin (Carbaryl)

CO + Cl = phosgene

Phosgene + methylamine = MIC

MIC—irritant to the lungs---

edema, fluid (cause of death, bronchospasms, corneal opacity

Hydrogen cyanide?

Sabotage or industrial accident?

World-wide Air Pollution Episode

November 27-December 10, 1962 Thousands of excess deaths in many cities including NYC, London, Boston, Paris

New Orleans Oct-Nov 1958 asthma deaths.

Hundreds Troubled by 'World Trade Center Cough‘ NYC fire fighters, school workers have 9/11 breathing problems, new studies say

Air Pollution

Transfer of harmful and/or of Natural/Synthetic materials into the atmosphere as a direct/indirect consequences of human activity (OECD).

Air Pollution Definition Based on System Approach

 

Types of Air Pollution

Personal air exposure

-It refers to exposure to dust, fumes and gases to which an individual exposes himself when he indulge himself in smoking

Occupational air exposure

-It represents the type of exposure of individuals to potentially harmful concentration of aerosols, vapors, and gases in their working environment.

Community air exposure

-This is most serious, complex, consists of varieties of assortment of pollution sources, meteorological factors, and wide variety of adverse social, economical, and health effects.

The Earth’s Great Spheres

Lithosphere- The lithosphere contains all of the cold, hard solid land of the planet's crust (surface), the semi-solid land underneath the crust, and the liquid land near the center of the planet

Hydrosphere- The hydrosphere contains all the solid, liquid, and gaseous water of the plane

Biosphere- The biosphere contains all the planet's living things. This sphere includes all of the microorganisms, plants, and animals of Ear

Atmosphere- The atmosphere contains all the air in Earth's system

Atmosphere

It is a mixture of gases that forms a layer of about 250 miles thick around the earth.

- Bottom 10-12 miles (Troposphere) is most important part in terms of

o Weather o Other aspects of Biogeochemical cycle

- The lowest 600 meters of Troposphere: Air Quality Studies

Composition of Air - 78% nitrogen, 21% oxygen, 1% carbon dioxide, water, other gases

Divided into four zones: - Troposphere- Stratosphere- Mesosphere- Thermosphere-

Stationary sources

o Point sources (Industrial processing, power plants, fuels combustion etc.) o Area sources (Residential heating coal gas oil, on site incineration, open burning etc.)

- Mobile sources

o Line sources (Highway vehicles, railroad locomotives, channel vessels etc.)  

Source of Air Pollution Natural Sources –Volcano, forest fire, dust storms, oceans, plants and trees

Anthropogenic Sources - created by human beings

Air Pollutants

Any substance occurring in the atmosphere that may have adverse effects on humans, animals, plant life, and/or inanimate materials.

Air pollutants have known or suspected harmful effects on human health and tironment.

Criteria Air Pollutants Based on health effects with measured air quality levels that violate the National Ambient Air Quality

Standards (NAAQS) (NAAQS)

-CO-NOx-SOx-VOCs-Particulates -Pb

Hazardous Air Pollutants

Predecessor: National Emission Standards for Hazardous Air Pollutants (NESHAPs) Clean Air Act Amendments of 1990 directed EPA to establish emission controls for 189 chemicals listed in

the Act.

-NOT based on health criteria-Based on Maximum Achievable Control Technology (MACT)

Non-Criteria Pollutants

In essence, all pollutants not included in the NAAQS and HAP lists Examples:

-CO-NaCl

Air Pollutants

Primary air pollutants - Materials that when released pose health risks in their unmodified forms or those emitted directly from identifiable sources.

Secondary air pollutants - Primary pollutants interact with one another, sunlight, or natural gases to produce new, harmful compounds

Primary Air Pollutants

Five major materials released directly into the atmosphere in unmodified forms.-Carbon monoxide -Sulfur dioxide-Nitrogen oxides-Hydrocarbons-Particulate matter

Carbon Monoxide

Produced by burning of organic material (coal, gas, wood, trash, etc.)

Automobiles biggest source (80%)

Cigarette smoke another major source

Toxic because binds to hemoglobin, reduces oxygen in blood

Not a persistent pollutant, combines with oxygen to form CO2

Most communities now meet EPA standards, but rush hour traffic can produce high CO levels

Sulphur Dioxide

Produced by burning sulfur containing fossil fuels (coal, oil)

Coal-burning power plants major source

Reacts in atmosphere to produce acids

One of the major components of acid rain

When inhaled, can be very corrosive to lung tissue

London-1306 banned burning of sea coal -1952 “killer fog”: 4,000 people died in 4 weeks

o tied to sulfur compounds in smog

 

Nitrogen Oxides

Produced from burning of fossil fuels

Contributes to acid rain, smog

Automobile engine main source

New engine technology has helped reduce, but many more cars

Hydrocarbons

Hydrocarbons - organic compounds with hydrogen, carbon

From incomplete burning or evaporated from fuel supplies

Major source is automobiles, but some from industry

Contribute to smog

Improvements in engine design have helped reduce

Particulates

Particulates - small pieces of solid materials and liquid droplets (2.5 mm and 10 mm)

Examples: ash from fires, asbestos from brakes and insulation, dust

Easily noticed: e.g. smokestacks

Can accumulate in lungs and interfere with the ability of lungs to exchange gases.

Some particulates are known carcinogens

Those working in dusty conditions at highest risk (e.g., miners)

Respirable Suspended Particulate Matter (RSPM) -PM1 having size <= 1µm: effects in alveoli-PM2.5 having size <= 2.5µm: effects trachea-PM10 having size <= 10µm: effects in nasal part only<

Secondary Pollutants

Ozone PAN (peroxy acetyl nitrate)

Photochemical smog

Aerosols and mists (H2SO4)

Ozone

Ozone (O3) is a highly reactive gas composed of three oxygen atoms.

It is both a natural and a man-made product that occurs in the Earth's upper atmosphere (the stratosphere) and lower atmosphere (the troposphere).

Tropospheric ozone – what we breathe -- is formed primarily from photochemical reactions between two major classes of air pollutants, volatile organic compounds (VOC) and nitrogen oxides (NOX).

PAN

Smog is caused by the interaction of some hydrocarbons and oxidants under the influence of sunlight giving rise to dangerous peroxy acetyl nitrate (PAN).

Photochemical smog

Photochemical smog is a mixture of pollutants which includes particulates, nitrogen oxides, ozone, aldehydes, peroxyethanoyl nitrate (PAN), unreacted hydrocarbons, etc. The smog often has a brown haze due to the presence of nitrogen dioxide. It causes painful eyes.

Aerosols and mists (H2SO4)

Aerosols and mists are very fine liquid droplets that cannot be effectively removed using traditional packed scrubbers.  These droplets can be formed from gas phase hydrolysis of halogenated acids (HCl, HF, HBr), metal halides, organohalides, sulfur trioxide (SO3), and phosphorous pentoxide (P2O5). 

Assignments

1. Can you explain the word ‘episode’ used in air pollution?2. Can you think why ‘mountains in a basin like area’ make the pollutants susceptible to accumulation?3. Can you tell two words making the word ‘smog’?4. Do you know that ‘soot’ is unburnt/burnt carbon particle?5. Why Earth Day is celebrated? Explain.6. Can you explain the significance of World Environment Day?7. What does ‘Earth Summit's means?8. Are CO and NOx ‘indicators or ‘pollutants’?9. Can you list direct/indirect consequences of human activity causing air pollution?10. Differentiate among personal/occupational/community air exposure. 11. Is environmental tobacco smoke (ETS) personal/occupational / community exposures?

12. Explain various spheres of the Earth. 13. Explain various sources of air pollution.14. Differentiate between troposphere/stratosphere/mesosphere. Which one is ideal for air pollution studies effecting living beings? 15. Differentiate between criteria/non-criteria/hazardous pollutants . Why O3 is not taken as criteria pollutants?

Ambient Air Pollution Monitoring

IntroductionMost frequently occurring pollutants in an urban environment are particulate matters (suspended particulate matter i.e. SPM and respirable suspended particulate matter i.e. RSPM), carbon monoxide (CO), hydrocarbons (HC), sulfur dioxide (SO2), nitrogen dioxide (NO2), ozone (O3) and photochemical oxidants.

 

The recommended criteria for siting the monitoring stations

The site is dependent upon the use/purpose of the results of the monitoring programs. The monitoring should be carried out with a purpose of compliance of air quality standards.

Monitoring must be able to evaluate impacts of new/existing air pollution sources.

Monitoring must be able to evaluate impacts of hazards due to accidental release of chemicals.

Monitoring data may be used for research purpose.

Type of ambient monitoring stations

Station type Description

Type A

Downtown pedestrian exposure station- In central business districts, in congested areas, surrounding by buildings, many pedestrians, average traffic flow > 10000 vehicles per day. Location of station- 0.5 m from curve; height 2.5 to 3.5 m from the ground.

Type B

Downtown neighbor hood exposure stations- In central business districts but not congested areas, less high rise buildings, average vehicles < 500 vehicles per day. Typical locations like parks, malls, landscapes areas etc.Location of station- 0.5 m from curve; height 2.5 to 3.5 m from the ground.

Type CResidential population exposure station – In the midst of the residential areas or sub-urban areas but not in central business districts. The station should be more than 100 m away from any street.

Type D Mesoscale stations – At appropriate height to collect meteorological and air quality data at upper elevation; main purpose to collect the trend of data variations not human exposure.

Type ENon-urban stations – In remote non-urban areas, no traffic, no industrial activity. Main purpose to monitor trend analysis. Location of station- 0.5 m from curve; height 2.5 to 3.5 m from the ground.

Type FSpecialized source survey stations – to determine the impact on air quality at specified location by an air pollution source under scrutiny. Location of station- 0.5 m from curve; height 2.5 to 3.5 m from the ground.

Frequency of data collection

Gaseous pollutants: continuous monitoring Particulates: once every three days

Number of stations

Minimum number is three. The location is dependent upon the wind rose diagram that gives predominant wind directions

and speed.

One station must be at upstream of predominant wind direction and other two must at downstream pre dominant wind direction.

More than three stations can also be established depending upon the area of coverage.

Components of ambient air sampling systems Four main components are:

Inlet manifold Air mover

collection medium

flow measurement device

Inlet manifold transports sampled pollutants from ambient air to collection medium or analytical device in an unaltered condition. The manifold should not be very long. Air mover provides force to create vacuum or lower pressure at the end of sampling systems. They are pumps. The collection mediums are liquid or solid sorbent or dissolving gases or filters or chamber for air analysis (automatic instruments). The flow device like rotameters measure the volume of air sampled.

Characteristics for ambient air sampling systems Five main characteristicss are:

collection efficiency sample stability

recovery

minimal interference

understanding the mechanism of collection

The first three must be 100% efficient. For e.g. for SO2, the sorbent should be such that at ambient temperature it may remove the SO2 from ambient atmosphere 100%. Sample must be stabled during the time between sampling and analysis. Recovery i.e. the analysis of particular pollutant must be 100% correct.

Basic considerations for sampling Sample must be representative in terms of time, location, and conditions to be studied. Sample must be large enough for accurate analysis.

The sampling rate must be such as to provide maximum efficiency of collection.

Duration of sampling must accurately reflect the fluctuations in pollution levels i.e. whether 1-hourly, 4-hourly, 6-hourly, 8-hourly, 24-hourly sampling.

Continuous sampling is preferred.

Pollutants must not be altered or modified during collection.

Errors in sampling by HVS Particulates may be lost in sampling manifold – so not too long or too twisted manifold must be

used. If ’isokinetic’ conditioned are not maintained, biased results may be obtained for particulate

matters.

Advantages of HVS High flow rate at low pressure drop High particulate storage capacity

No moisture regain

high collection efficiency

Low coast

Not appreciable increase in air flow resistance

Filter is 99% efficient and can collect the particles as fine as 0.3 µm

Absorption principle is 99% efficient in collecting the gases

Stack Monitoring: techniques & instrumentation

Sampling

The sample collected must be representative in terms of time and location.

The sample volume should be large enough to permit accurate analysis. The sampling rate must be such as to provide maximum efficiency of collection. The contaminants must not be modified or altered in the process of collection.

Diagrammatic view of stack sampling

Impingers are glass bubble tubes designed for the collection of airborne particles into a liquid medium (Figure 1).

When using an air sampler, a known volume of air bubbles is pumped through the glass tube that contains

a liquid specified in the method.

The liquid is then analyzed to determine airborne concentrations.

Figure 1: Glass Impinger

Selection of sampling location The sampling point should be as far as possible from any disturbing influence, such as elbows, bends,

transition pieces, baffles. The sampling point, wherever possible should be at a distance of 5-10 diameters down-stream from any

obstruction and 3-5 diameters up-stream from similar disturbance.

Size of sampling point The size of the sampling point may be made in the range of 7-10 cm, in diameter.

Traverse points For the sample become representative, it should be collected at various points across the stack. The number of traverse points may be selected with reference to Table 1.

Table 1: Traverse Points

Cross-section area of stack sq. m

No. of Points

0.2 40.2 to 2.5 12

2.5 and above 20

In circular stacks, traverse points are located at the center of equal annular areas across two perpendicular diameters as shown in Figure 2

Figure 2 In case of rectangular stacks, the area may be divided in to 12 to 25 equal areas and the centers for each area are fixed. (Figure 3)

Figure 3

Isokinetic conditions Isokinetic conditions exist when the velocity in the stack ‘Vs’ equals the velocity at the top of the probe

nozzle ‘Vn’ at the sample point (Figure 4).

Figure 4

Ambient Air Pollution Monitoring

IntroductionMost frequently occurring pollutants in an urban environment are particulate matters (suspended particulate matter i.e. SPM and respirable suspended particulate matter i.e. RSPM), carbon monoxide (CO), hydrocarbons (HC), sulfur dioxide (SO2), nitrogen dioxide (NO2), ozone (O3) and photochemical oxidants.

 

The recommended criteria for siting the monitoring stations

The site is dependent upon the use/purpose of the results of the monitoring programs. The monitoring should be carried out with a purpose of compliance of air quality standards.

Monitoring must be able to evaluate impacts of new/existing air pollution sources.

Monitoring must be able to evaluate impacts of hazards due to accidental release of chemicals.

Monitoring data may be used for research purpose.

Type of ambient monitoring stations

Station type Description

Type A

Downtown pedestrian exposure station- In central business districts, in congested areas, surrounding by buildings, many pedestrians, average traffic flow > 10000 vehicles per day. Location of station- 0.5 m from curve; height 2.5 to 3.5 m from the ground.

Type B Downtown neighbor hood exposure stations- In central business districts but not

congested areas, less high rise buildings, average vehicles < 500 vehicles per day. Typical locations like parks, malls, landscapes areas etc.Location of station- 0.5 m from curve; height 2.5 to 3.5 m from the ground.

Type CResidential population exposure station – In the midst of the residential areas or sub-urban areas but not in central business districts. The station should be more than 100 m away from any street.

Type D Mesoscale stations – At appropriate height to collect meteorological and air quality data at upper elevation; main purpose to collect the trend of data variations not human exposure.

Type ENon-urban stations – In remote non-urban areas, no traffic, no industrial activity. Main purpose to monitor trend analysis. Location of station- 0.5 m from curve; height 2.5 to 3.5 m from the ground.

Type FSpecialized source survey stations – to determine the impact on air quality at specified location by an air pollution source under scrutiny. Location of station- 0.5 m from curve; height 2.5 to 3.5 m from the ground.

Frequency of data collection

Gaseous pollutants: continuous monitoring Particulates: once every three days

Number of stations

Minimum number is three. The location is dependent upon the wind rose diagram that gives predominant wind directions

and speed.

One station must be at upstream of predominant wind direction and other two must at downstream pre dominant wind direction.

More than three stations can also be established depending upon the area of coverage.

Components of ambient air sampling systems Four main components are:

Inlet manifold Air mover

collection medium

flow measurement device

Inlet manifold transports sampled pollutants from ambient air to collection medium or analytical device in an unaltered condition. The manifold should not be very long. Air mover provides force to create vacuum or lower pressure at the end of sampling systems. They are pumps. The collection mediums are liquid or solid sorbent or dissolving gases or filters or chamber for air analysis (automatic instruments). The flow device like rotameters measure the volume of air sampled.

Characteristics for ambient air sampling systems Five main characteristicss are:

collection efficiency sample stability

recovery

minimal interference

understanding the mechanism of collection

The first three must be 100% efficient. For e.g. for SO2, the sorbent should be such that at ambient temperature it may remove the SO2 from ambient atmosphere 100%. Sample must be stabled during the time between sampling and analysis. Recovery i.e. the analysis of particular pollutant must be 100% correct.

Basic considerations for sampling Sample must be representative in terms of time, location, and conditions to be studied. Sample must be large enough for accurate analysis.

The sampling rate must be such as to provide maximum efficiency of collection.

Duration of sampling must accurately reflect the fluctuations in pollution levels i.e. whether 1-hourly, 4-hourly, 6-hourly, 8-hourly, 24-hourly sampling.

Continuous sampling is preferred.

Pollutants must not be altered or modified during collection.

Errors in sampling by HVS Particulates may be lost in sampling manifold – so not too long or too twisted manifold must be

used. If ’isokinetic’ conditioned are not maintained, biased results may be obtained for particulate

matters.

Advantages of HVS High flow rate at low pressure drop High particulate storage capacity

No moisture regain

high collection efficiency

Low coast

Not appreciable increase in air flow resistance

Filter is 99% efficient and can collect the particles as fine as 0.3 µm

Absorption principle is 99% efficient in collecting the gases

Stack Monitoring: techniques & instrumentation

Sampling

The sample collected must be representative in terms of time and location.

The sample volume should be large enough to permit accurate analysis. The sampling rate must be such as to provide maximum efficiency of collection. The contaminants must not be modified or altered in the process of collection.

Diagrammatic view of stacksampling

Impingers are glass bubble tubes designed for the collection of airborne particles into a liquid medium (Figure 1).

When using an air sampler, a known volume of air bubbles is pumped through the glass tube that contains a liquid specified in the method.

The liquid is then analyzed to determine airborne concentrations.

Figure 1: Glass Impinger

Selection of sampling location The sampling point should be as far as possible from any disturbing influence, such as elbows, bends,

transition pieces, baffles. The sampling point, wherever possible should be at a distance of 5-10 diameters down-stream from any

obstruction and 3-5 diameters up-stream from similar disturbance.

Size of sampling point The size of the sampling point may be made in the range of 7-10 cm, in diameter.

Traverse points For the sample become representative, it should be collected at various points across the stack. The number of traverse points may be selected with reference to Table 1.

Table 1: Traverse Points

Cross-section area of stack sq. m

No. of Points

0.2 40.2 to 2.5 12

2.5 and above 20

In circular stacks, traverse points are located at the center of equal annular areas across two perpendicular diameters as shown in Figure 2

Figure 2 In case of rectangular stacks, the area may be divided in to 12 to 25 equal areas and the centers for each area are fixed. (Figure 3)

Figure 3

Isokinetic conditions Isokinetic conditions exist when the velocity in the stack ‘Vs’ equals the velocity at the top of the probe

nozzle ‘Vn’ at the sample point (Figure 4).

Figure 4

Experimental analysis: Gaseous & particulates; standards & limits

Principles of Sampling and Analysis

The components of an air pollution monitoring system include the -collection or sampling of pollutants both from the ambient air and from specific sources, -the analysis or measurement of the pollutant concentrations, and -the reporting and use of the information collected.

Emissions data collected from point sources are used to determine compliance with air pollution regulations, determine the effectiveness of air pollution control technology, evaluate production efficiencies, and support scientific research.

The EPA has established ambient air monitoring methods for the criteria pollutants, as well as for toxic organic (TO) compounds and inorganic (IO) compounds.

The methods specify precise procedures that must be followed for any monitoring activity related to the compliance provisions of the Clean Air Act.

These procedures regulate sampling, analysis, calibration of instruments, and calculation of emissions.

The concentration is expressed in terms of mass per unit volume, usually micrograms per cubic meter (µg/m3).

Particulate Monitoring Particulate monitoring is usually accomplished with manual measurements and subsequent laboratory

analysis. A particulate matter measurement uses gravimetric principles. Gravimetric analysis refers to the

quantitative chemical analysis of weighing a sample, usually of a separated and dried precipitate.

In this method, a filter-based high-volume sampler (a vacuum- type device that draws air through a filter or absorbing substrate) retains atmospheric pollutants for future laboratory weighing and chemical analysis. Particles are trapped or collected on filters, and the filters are weighed to determine the volume of the pollutant. The weight of the filter with collected pollutants minus the weight of a clean filter gives the amount of particulate matter in a given volume of air.

Chemical analysis can be done by atomic absorption spectrometry (AAS), atomic fluorescence spectrometry (AFS), inductively couple plasma (ICP) spectroscopy, and X-ray fluorescence (XRF) spectroscopy.

Atomic Absorption Spectrometry (AAS)

AAS is a sensitive means for the quantitative determination of more than 60 metals or metalloid elements. Principle: This technique operates by measuring energy changes in the atomic state of the analyte. For

example, AAS is used to measure lead in particulate monitoring.

Figure: Atomic absorption spectrometry

Particles are collected by gravimetric methods in a Teflon (PTFE) filter, lead is acid-extracted from the filter.

The aqueous sample is vaporized and dissociates into its elements in the gaseous state. The element being measured, in this case lead, is aspirated into a flame or injected into a graphite furnace and atomized.

A hollow cathode or electrode less discharge lamp for the element being determined provides a source of that metal's particular absorption wavelength.

The atoms in the unionized or "ground" state absorb energy, become excited, and advance to a higher energy level.

A detector measures the amount of light absorbed by the element, hence the number of atoms in the ground state in the flame or furnace.

The data output from the spectrometer can be recorded on a strip chart recorder or processed by computer.

Determination of metal concentrations is performed from prepared calibration curves or read directly from the instrument.

Gaseous pollutant monitoring

Gaseous pollutant monitoring can be accomplished using various measurement principles. Some of the most common techniques to analyze gaseous pollutants include

-Spectrophotometry, -Chemi-luminescence, -Gas chromatography-flame ionization detector (GC-FID), - Gas chromatography-mass spectrometry (GC-MS), and - Fourier transform infrared spectroscopy (FTIR).

With all sampling and analysis procedures, the end result is quantitative data.

The validity of the data depends on the accuracy and precision of the methods used in generating the data.

The primary quality control measure is calibration.

Calibration checks the accuracy of a measurement by establishing the relationship between the output of a measurement process and a known input.

Table 1. Methods of Measuring and Analyzing Air Pollutants

Method Variable

Measured Principle

Gravimetric PM10, PM2.5 Particles are trapped or collected on filters, and the filters are weighed to determine the volume of the pollutant.

Atomic absorption spectrometry (AAS)

more than 60 metals or metalloid elements (e.g. Pb,

Hg, Zn)

This technique operates by measuring energy changes in the atomic state of the analyte.  Emitted radiation is a function of atoms present in the sample.

Spectrophotometry SO2, O3 Measure the amount of light that a sample absorbs.  The amount of light absorbed indicates the amount of analyte present in the sample.

Chemiluminescence SO2, O3 Based upon the emission spectrum of an excited species that is formed in the course of a chemical reaction.

Gas chromatography (GC) - flame ionization

detector (FID) VOC Responds in proportion to number of carbon atoms in gas sample.

Gas chromatography-mass spectrometry

(GC-MS) VOC

Mass spectrometers use the difference in mass-to-charge ratio (m/z) of ionized atoms or molecules to separate them from each other.

Fourier Transform Infrared Spectroscopy

(FTIR) CO, VOC, CH4

Sample absorbs infrared radiation and difference in absorption is measured.

Spectrophotometry

A spectrophotometer measures the amount of light that a sample absorbs. The instrument operates by passing a beam of light through a sample and measuring the intensity of light

reaching a detector.

Spectrophotometry commonly used to measure sulfur dioxide (SO2) concentrations.

The amount of light absorbed indicates the amount of sulfur dioxide present in the sample.

Figure: Schematic of a UV-VIS spectrophotometer

Chemiluminescence

An ambient air sample is mixed with excess ozone in a special sample cell. A portion of the NO present is converted to an activated NO2 which returns to a lower energy state and in the process emits light. This phenomenon is called chemiluminescence.

Figure: Chemical reaction to determine oxides of nitrogen by chemiluminescence

Chemiluminescence methods for determining components of gases originated with the need for highly sensitive means for determining atmospheric pollutants such as ozone, oxides of nitrogen, and sulfur compounds.

The intensity of this light can be measured with a photomultiplier tube and is proportional to the amount of NO in the sample. A second reaction measures the total oxides of nitrogen in the air sample and in turn, the concentration of NO2 can be calculated.

Gas Chromatography (GC)

Gas chromatography (GC) coupled with a flame ionization detector (FID) is employed for qualitative identification and quantitative determination of volatile organic compounds (VOCs) in air pollution monitoring.

The GC, consists of a column, oven and detector. In the gas chromatograph, a sample goes to the column,

separates into individual compounds and proceeds through the hydrogen flame ionization detector.

Figure: Schematic gas chromatography

The flame in a flame ionization detector is produced by the combustion of hydrogen and air. When a sample is introduced, hydrocarbons are combusted and ionized, releasing electrons.

A collector with a polarizing voltage located near the flame attracts the free electrons, producing a current that is proportional to the amount of hydrocarbons in the sample.

The signal from the flame ionization detector is then amplified and output to a display or external device.

Gas chromatography-mass spectrometry (GC-MS) instruments have also been used for identification of volatile organic compounds. Mass spectrometers use the difference in mass-to-charge ratio (m/z) of ionized atoms or molecules to separate them from each other. Mass spectrometry is useful for quantification of atoms or molecules and also for determining chemical and structural information about molecules.

Fourier Transform Infrared Spectroscopy

FTIR can detect and measure both criteria pollutants and toxic pollutants in ambient air

FTIR can directly measure more than 120 gaseous pollutants in the ambient air, such as carbon monoxide, sulfur dioxide, and ozone.

The technology is based on the fact that every gas has its own "fingerprint," or absorption spectrum.

Figure: FTIR can directly measure both criteria pollutants and toxic pollutants in the ambient air.

The FTIR sensor monitors the entire infrared spectrum and reads the different fingerprints of the gases present in the ambient air.

Carbon monoxide is monitored continuously by analyzers that operate on the infrared absorption principle.

Ambient air is drawn into a sample chamber and a beam of infrared light is passed through it.

CO absorbs infrared radiation, and any decrease in the intensity of the beam is due to the presence of CO molecules.

This decrease is directly related to the concentration of CO in the air.

A special detector measures the difference in the radiation between this beam and a duplicate beam passing through a reference chamber with no CO present.

This difference in intensity is electronically translated into a reading of the CO present in the ambient air, measured in parts per million.

National Ambient Air Quality StandardsPOLLUTANTS AVERAGE TIME CONCENTRATION

sulphur dioxide (SO2)Annual average

24 hour60 µg/cubic m80 µg/cubic m

Oxides of Nitrogen (NO2)A.A24H

60 µg/cubic m80 µg/cubic m

Suspended Particulate Matter (SPM)

A.A24H

140µg/cubic m200µg/cubic m

LeadA.A24H

0.75 µg/cubic m1.0 µg/cubic m

Carbon MonoxideA.A24H

2.0 µg/cubic m84.0 µg/cubic m

Respirable Particulate Matter (RPM)

A.A24H

60 µg/cubicm100 µg/cubic m

NAAQS by USEPA 2006

Pollutant Primary Stds. Averaging Times Secondary Stds.

Carbon Monoxide9 ppm (10 mg/cubic m) 8-hour(1) None

35 ppm (40 mg/cubic m)

1-hour(1) None

Lead 1.5 µg/cubic m Quarterly Average Same as Primary

Nitrogen Dioxide0.053 ppm (100

µg/cubic m)Annual (Arithmetic Mean) Same as Primary

Particulate Matter (PM10)

Revoked(2) Annual(2) (Arith. Mean)

150 µg/cubic m 24-hour(3)

Particulate Matter (PM2.5)

15.0 µg/cubic m Annual(4) (Arith. Mean) Same as Primary

35 µg/cubic m 24-hour(5)

Ozone0.08 ppm 8-hour(6) Same as Primary

0.12 ppm1-hour(7) (Applies only in

limited areas)Same as Primary

Sulfur Oxides

0.03 ppm Annual (Arith. Mean) -------

0.14 ppm 24-hour(1) -------

------- 3-hour(1)0.5 ppm (1300

µg/cubic m)(1)Not to be exceeded more than once per year.(2)Due to a lack of evidence linking health problems to long-term exposure to coarse particle pollution, the agency revoked the annual PM10 standard in 2006 (effective December 17, 2006).(3) Not to be exceeded more than once per year on average over 3 years.(4) To attain this standard, the 3-year average of the weighted annual mean PM2.5 concentrations from single or multiple community-oriented monitors must not exceed 15.0 µg/cubic metre.(5) To attain this standard, the 3-year average of the 98th percentile of 24-hour concentrations at each population-oriented monitor within an area must not exceed 35 µg/cubic metre (effective December 17, 2006).

(6) To attain this standard, the 3-year average of the fourth-highest daily maximum 8-hour average ozone concentrations measured at each monitor within an area over each year must not exceed 0.08 ppm. (7) (a) The standard is attained when the expected number of days per calendar year with maximum hourly average concentrations above 0.12 ppm is < 1, as determined by appendix H. (b) As of June 15, 2005 EPA revoked the 1-hour ozone standard in all areas except the fourteen 8-hour ozone nonattainment Early Action Compact (EAC) Areas.

WHO Air Quality Guidelines Value

POLLUTANTS AVERAGE TIME AQG value

Particulate matterPM2.5

PM10

1 year 24 hour(99th percentile)

1 year 24 hour(99th percentile)

10 µg/cubic metre

25 µg/cubic metre

20 µg/cubic metre

50 µg/cubic metre

Ozone, O3 8 hour, daily maximum 100 µg/cubic

metre

Nitrogen dioxide, NO2 1 year 1 hour

40µg/cubic metre

200µg/cubic metre

Sulfur dioxide, SO2 24 hour 10 minute

20 µg/cubic metre

500 µg/cubic metre

References

USEPA, 2007. Online literature from www.epa.govWHO, 2005. WHO air quality guidelines global update 2005, WHOLIS number E87950.CPCB 2006, Central Pollution Control Board. http://www.cpcb.nic.in/standard2.htm

Air pollution effects : On living and non living beings

Human Health Effects

Exposure to air pollution is associated with numerous effects on human health, including pulmonary, cardiac, vascular, and neurological impairments.

The health effects vary greatly from person to person. High-risk groups such as the elderly, infants, pregnant women, and sufferers from chronic heart and lung diseases are more susceptible to air pollution.

Children are at greater risk because they are generally more active outdoors and their lungs are still developing.

Exposure to air pollution can cause both acute (short-term) and chronic (long-term) health effects.

Acute effects are usually immediate and often reversible when exposure to the pollutant ends. Some acute health effects include eye irritation, headaches, and nausea.

Chronic effects are usually not immediate and tend not to be reversible when exposure to the pollutant ends. - Some chronic health effects include decreased lung capacity and lung cancer resulting from long-term exposure to toxic air pollutants.

Effects on Human respiratory system

Both gaseous and particulate air pollutants can have negative effects on the lungs.

Solid particles can settle on the walls of the trachea, bronchi, and bronchioles.

Continuous breathing of polluted air can slow the normal cleansing action of the lungs and result in more particles reaching the lower portions of the lung.

Damage to the lungs from air pollution can inhibit this process and contribute to the occurrence of respiratory diseases such as bronchitis, emphysema, and cancer.

Table 1:  Sources, Health and Welfare Effects for Criteria

Pollutant Description Sources Health Effects Welfare Effects Carbon Monoxide (CO)

Colorless, odorless gas

Motor vehicle exhaust, indoor sources include kerosene or wood burning stoves.

Headaches, reduced mental alertness, heart attack, cardiovascular diseases, impaired fetal development, death.

Contribute to the formation of smog.

Sulfur Dioxide (SO2)

Colorless gas that dissolves in water vapor to form acid, and interact with other gases and particles in the air.

Coal-fired power plants, petroleum refineries, manufacture of sulfuric acid and smelting of ores containing sulfur.

Eye irritation, wheezing, chest tightness, shortness of breath, lung damage.

Contribute to the formation of acid rain, visibility impairment, plant and water damage, aesthetic damage.

Nitrogen Dioxide (NO2)

Reddish brown, highly reactive gas.

Motor vehicles, electric utilities, and other industrial, commercial, and residential sources that burn fuels.

Susceptibility to respiratory infections, irritation of the lung and respiratory symptoms (e.g., cough, chest pain, difficulty breathing).

Contribute to the formation of smog, acid rain, water quality deterioration, global warming, and visibility impairment.

Ozone (O3) Gaseous pollutant when it is formed in the troposphere.

Vehicle exhaust and certain other fumes.  Formed from other air pollutants in the presence of sunlight.

Eye and throat irritation, coughing, respiratory tract problems, asthma, lung damage.

Plant and ecosystem damage.

Lead (Pb) Metallic element Metal refineries, lead smelters, battery manufacturers, iron and steel producers.

Anemia, high blood pressure, brain and kidney damage, neurological disorders, cancer, lowered IQ.

Affects animals and plants, affects aquatic ecosystems.

Particulate Very small particles of Diesel engines, power Eye irritation, asthma, Visibility impairment,

Matter (PM) soot, dust, or other matter, including tiny droplets of liquids.

plants, industries, windblown dust, wood stoves.

bronchitis, lung damage, cancer, heavy metal poisoning, cardiovascular effects.

atmospheric deposition, aesthetic damage.

Table 2: Sources, Effects of Air Pollutants on Vegetables

Pollutants Sources Effects on VegetablesAldehydes Photochemical reactions The upper portions of Alfalfa etc. will be affected to

Narcosis if 250 ppm of aldehydes is present for 2 hrs duration.

Ozone (O3) Photochemical reaction of hydrocarbon and nitrogen oxides from fuel combustion, refuse burning, and evaporation from petroleum products.

All ages of tobacco leaves, beans, grapes, pine, pumpkins and potato are affected. Fleck, stipple, bleaching, bleached spotting, pigmentation, growth suppression, and early abscission are the effects.

Peroxy Acetyl Nitrate (PAN)

The sources of PAN are the same as ozone

Young spongy cells of plants are affected if 0.01 ppm of PAN is present in the ambient air for more than 6 hrs.

Nitrogen dioxide (NO2)

High temperature combustion of coal, oil, gas, and gasoline in power plants and internal combustion engines.

Irregular, white or brown collapsed lesion on intercostals tissue and near leaf margin. Suppressed growth is observed in many plants.

Ammonia & Sulfur dioxide

Thermal power plants, oil and petroleum refineries.

Bleached spots, bleached areas between veins, bleached margins, chlorosis, growth suppression, early abscission, and reduction in yield and tissue collapse occur.

Chlorine (Cl2) Leaks in chlorine storage tanks, hydrochloric acid mists.

If 0.10 ppm is present for at least 2 hrs, the epidermis and mesophyll of plants will be affected.

Hydrogen fluoride, Silicon tetrafluoride

Phosphate rock processing, aluminum industry, and ceramic works and fiberglass manufacturing.

Epidermis and mesophyll of grapes, large seed fruits, pines and fluorosis in animals occur if 0.001 ppm of HF is present for 5 weeks.

Pesticides & Herbicides

Agricultural operations Defoliation, dwarfing, curling, twisting, growth reduction and killing of plants may occur.

Particulates Cement industries, thermal power plants, blasting, crushing and processing industries.

Affects quality of plants, reduces vigor & hardness and interferences with photosynthesis due to plugging leaf stomata and blocking of light.

Mercury (Hg) Processing of mercury containing ores, burning of coal and oil.

Greenhouse crops, and floral parts of all vegetations are affected; abscission and growth reduction occur in most of the plants.

 

 

Air pollution control : Principles of controls, source control

Source Control Technology Air quality management sets the tools to control air pollutant emissions. Control measurements describes the equipment, processes or actions used to reduce air pollution.

The extent of pollution reduction varies among technologies and measures.

The selection of control technologies depends on environmental, engineering, economic factors and pollutant type.

Settling Chambers Settling chambers use the force of gravity to remove solid particles.

The gas stream enters a chamber where the velocity of the gas is reduced. Large particles drop out of the gas and are recollected in hoppers. Because settling chambers are effective in removing only larger particles, they are used in conjunction with a more efficient control device.

Figure: Settling chambers

Cyclones

The general principle of inertia separation is that the particulate-laden gas is forced to change direction. As gas changes direction, the inertia of the particles causes them to continue in the original direction and be separated from the gas stream.

The walls of the cyclone narrow toward the bottom of the unit, allowing the particles to be collected in a hopper.

The cleaner air leaves the cyclone through the top of the chamber, flowing upward in a spiral vortex, formed within a downward moving spiral.

Cyclones are efficient in removing large particles but are not as efficient with smaller particles. For this reason, they are used with other particulate control devices.

Venturi Scrubbers

Venturi scrubbers use a liquid stream to remove solid particles.

In the venturi scrubber, gas laden with particulate matter passes through a short tube with flared ends and a constricted middle.

This constriction causes the gas stream to speed up when the pressure is increased.

The difference in velocity and pressure resulting from the constriction causes the particles and water to mix and combine.

The reduced velocity at the expanded section of the throat allows the droplets of water containing the particles to drop out of the gas stream.

Venturi scrubbers are effective in removing small particles, with removal efficiencies of up to 99 percent.

Figure: Fabric filter (baghouse) components

One drawback of this device, however, is the production of wastewater.

Fabric filters, or baghouses, remove dust from a gas stream by passing the stream through a porous fabric. The fabric filter is efficient at removing fine particles and can exceed efficiencies of 99 percent in most applications.

The selection of the fiber material and fabric construction is important to baghouse performance.

The fiber material from which the fabric is made must have adequate strength characteristics at the maximum gas temperature expected and adequate chemical compatibility with both the gas and the collected dust.

One disadvantage of the fabric filter is that high-temperature gases often have to be cooled before contacting the filter medium.

Electrostatic Precipitators (ESPs)

An ESP is a particle control device that uses electrical forces to move the particles out of the flowing gas stream and onto collector plates.

The ESP places electrical charges on the particles, causing them to be attracted to oppositely charged metal plates located in the precipitator.

The particles are removed from the plates by "rapping" and collected in a hopper located below the unit.

The removal efficiencies for ESPs are highly variable; however, for very small particles alone, the removal efficiency is about 99 percent.

Electrostatic precipitators are not only used in utility applications but also other industries (for other exhaust gas particles) such as cement (dust), pulp & paper (salt cake & lime dust), petrochemicals (sulfuric acid mist), and steel (dust & fumes).

Figure: Electrostatic precipitator components

Control of gaseous pollutants from stationary sources

The most common method for controlling gaseous pollutants is the addition of add-on control devices to recover or destroy a pollutant.

There are four commonly used control technologies for gaseous pollutants: - Absorption,

- Adsorption, - Condensation, and - Incineration (combustion)

Absorption

 

The removal of one or more selected components from a gas mixture by absorption is probably the most important operation in the control of gaseous pollutant emissions.

Absorption is a process in which a gaseous pollutant is dissolved in a liquid.

As the gas stream passes through the liquid, the liquid absorbs the gas, in much the same way that sugar is absorbed in a glass of water when stirred.

Absorbers are often referred to as scrubbers, and there are various types of absorption equipment.

The principal types of gas absorption equipment include spray towers, packed columns, spray chambers, and venture scrubbers.

In general, absorbers can achieve removal efficiencies grater than 95 percent. One potential problem with absorption is the generation of waste-water, which converts an air pollution problem to a water pollution problem.

Adsorption

When a gas or vapor is brought into contact with a solid, part of it is taken up by the solid. The molecules that disappear from the gas either enter the inside of the solid, or remain on the outside attached to the surface. The former phenomenon is termed absorption (or dissolution) and the latter adsorption.

The most common industrial adsorbents are activated carbon, silica gel, and alumina, because they have enormous surface areas per unit weight.

Activated carbon is the universal standard for purification and removal of trace organic contaminants from liquid and vapor streams. Carbon adsorption systems are either regenerative or non-regenerative. - Regenerative system usually contains more than one carbon bed. As one bed actively removes pollutants, another bed is being regenerated for future use.

- Non-regenerative systems have thinner beds of activated carbon. In a non-regenerative adsorber, the spent carbon is disposed of when it becomes saturated with the pollutant.

Condensation

Condensation is the process of converting a gas or vapor to liquid. Any gas can be reduced to a liquid by lowering its temperature and/or increasing its pressure.

Condensers are typically used as pretreatment devices. They can be used ahead of absorbers, absorbers, and incinerators to reduce the total gas volume to be treated by more expensive control equipment. Condensers used for pollution control are contact condensers and surface condensers.

In a contact condenser, the gas comes into contact with cold liquid.

In a surface condenser, the gas contacts a cooled surface in which cooled liquid or gas is circulated, such as the outside of the tube.

Removal efficiencies of condensers typically range from 50 percent to more than 95 percent, depending on design and applications.

Incineration Incineration, also known as combustion, is most used to control the emissions of organic compounds from

process industries. This control technique refers to the rapid oxidation of a substance through the combination of oxygen with

a combustible material in the presence of heat. When combustion is complete, the gaseous stream is converted to carbon dioxide and water vapor.

Equipment used to control waste gases by combustion can be divided in three categories: - Direct combustion or flaring, - Thermal incineration and

- Catalytic incineration.

Direct combustor Direct combustor is a device in which air and all the combustible waste gases react at the burner.

Complete combustion must occur instantaneously since there is no residence chamber. A flare can be used to control almost any emission stream containing volatile organic compounds. Studies

conducted by EPA have shown that the destruction efficiency of a flare is about 98 percent. In thermal incinerators the combustible waste gases pass over or around a burner flame into a residence chamber where oxidation of the waste gases is completed. Thermal incinerators can destroy gaseous pollutants at efficiencies of greater than 99 percent when operated correctly.

Thermal incinerator general case

Catalytic incinerators are very similar to thermal incinerators. The main difference is that after passing through the flame area, the gases pass over a catalyst bed. A catalyst promotes oxidation at lower temperatures, thereby reducing fuel costs. Destruction efficiencies greater than 95 percent are possible using a catalytic incinerator.

Catalytic incinerator

References

USEPA, 2007. Online literature from www.epa.gov Rao, M.N. and Rao, H. V. N., 1993. Air Pollution, Tata Mc-Graw Hill, New Delhi.

Murty, B. P., 2004. Environmental Meteorology, I.K. International Pvt. Ltd., New Delhi.

Nevers, N.D. 2000. Air Pollution Control Engineering, Second Edition, Pub., McGraw Hill, New York.

Cheremisinoff, N.P., 2002. Handbook of Air Pollution Prevention and Control, Pub., Butterworth-Heinemann, Elsevier Science, USA.

THE ECOLOGICAL CRISIS - A Philosophical Perspective

Transport and diffusion from source to receptor

Air Pollutant Cycle

Dispersion

General mean air motion Turbulent velocity fluctuationsTurbulent velocity fluctuations

Diffusion due to concentration gradients – from plumes

Aerodynamic characteristics of pollution

Particles - Size- Shape- Weight

Not always completely understood

Two types:

Atmospheric heating - Causes natural convection currents --- discussed - Thermal eddies

Mechanical turbulence - Results from shear wind effects- Result from air movement over the earth�s surface, influenced by location of buildings and relative roughness of terrain.

Lapse Rate

Important characteristic of atmosphere is ability to resist vertical motion: stability Affects ability to disperse pollutants

When small volume of air is displaced upward

- Encounters lower pressure - Expands to lower temperature- Assume no heat transfers to surrounding atmosphere - Called adiabatic expansion

Adiabatic Expansion

To determine the change in temp. w/ elevation due to adiabatic expansion .- Atmosphere considered a stationary column of air in a gravitational field - Gas is a dry ideal gas - Ignoring friction and inertial effects

( dT/dz)adiabatic perfect gas = - (g M/ Cp)

T = temperature

z = vertical distance

g = acceleration due to gravity

M = molecular weight of air

Cp = heat capacity of the gas at constant pressure

Adiabatic Expansion

( dT/dz)adiabatic perfect gas = -0.0098°C/m or

( dT/dz)adiabatic perfect gas = -5.4°F/ft

Change in Temp. with change in height

Lapse rate Lapse rate is the negative of temperature gradient Dry adiabatic lapse rate =

Metric:Metric:G = - 1°C/100m orSI:G = - 5.4°F/1000ft

Important is ability to resist vertical motion: stability.

Comparison of G to actual environment lapse rate indicates stability of atmosphere.

Degree of stability is a measure of the ability of the atmosphere to disperse pollutants.

Atmospheric Stability

Affects dispersion of pollutants Temperature/elevation relationship principal determinant of atmospheric stability

Stable- Little vertical mixing- Pollutants emitted near surface tend to stay there- Environmental lapse rate is same as the dry adiabatic lapse rate

4 common scenarios

Stability Classes

Developed for use in dispersion models Developed for use in dispersion models

Stability classified into 6 classes (A – F)A: strongly unstableB: moderately unstableC: slightly unstableD: neutralE: slightly stableF: moderately stable

Vertical Temperature Profiles  

Environmental lapse rate (ELR)Dry adiabatic lapse rate (DALR)

If, ELR > DALR =sub adiabatic

condition, atmosphere is stable. ELR >> DALR= Inversion

conditions. Very stable atmosphere.

ELR= DALR= atmosphere is neutral.

ELR< DALR = super adiabatic condition, atmosphere is unstable.

Shapes of plumes depends upon atmospheric stability conditions.

Mixing Height of atmosphere

The height of the base of the inversion layer from ground surface.

MORNING AND AFTERNOON MIXING DEPTH CALCULATIONS

General Characteristics of Stack Plumes

Dispersion of pollutants Wind – carries pollution downstream from source

Atmospheric turbulence -- causes pollutants to

fluctuate from mainstream in vertical and crosswind directions

Mechanical & atmospheric heating both present at same time but in varying ratios

Affect plume dispersion differently

Plume Types Plume types are important because they help us understand under what conditions there will be higher

concentrations of contaminants at ground level.

Looping Plume

High degree of convective turbulence

Superadiabatic lapse rate -- strong instabilities

Associated with clear daytime conditions accompanied by strong solar heating & light winds

High probability of high concentrations sporadically at ground level close to stack.

Occurs in unstable atmospheric conditions.

Coning Plume

Stable with small-scale turbulence

Associated with overcast moderate to strong winds

Roughly 10° cone

Pollutants travel fairly long distances before reaching ground level in significant amounts

Occurs in neutral atmospheric conditions

Fanning Plume

Occurs under large negative lapse rate

Strong inversion at a considerable distance above the stack

Extremely stable atmosphere

Little turbulence

If plume density is similar to air, travels downwind at approximately same elevation

Lofting Plume

Favorable in the sense that fewer impacts at ground level.

Pollutants go up into environment.

They are created when atmospheric conditions are unstable above the plume and stable below.

Fumigation

Most dangerous plume: contaminants are all coming down to ground level.

They are created when atmospheric conditions are stable above the plume and unstable below.

This happens most often after the daylight sun has warmed the atmosphere, which turns a night time fanning plume into fumigation for about a half an hour.

References USEPA, 2007. Online literature from www.epa.gov

Meteorology and Air Quality Modeling Support for Measurement Projects http://files.harc.edu/Sites/TERC/About/Events/ Other200503/MeteorologyAndAirQuality.pdf

Rao, M.N. and Rao, H. V. N., 1993. Air Pollution, Tata Mc-Graw Hill, New Delhi.

Murty, B. P., 2004. Environmental Meteorology, I.K. International Pvt. Ltd., New Delhi.

Nevers, N.D. 2000. Air Pollution Control Engineering, Second Edition, Pub., McGraw Hill, New York.

Cheremisinoff, N.P., 2002. Handbook of Air Pollution Prevention and Control, Pub., Butterworth-Heinemann, Elsevier Science, USA.

Air Quality Modelling

What does model means?

Models reflects a mathematical description of hypothesis conveying the behavior of some physical process or other.

Not exact replica but contain some of nature’s essential elements.

What is mathematical modelling?

When the process of problem reduction or solution involves transforming some idealized form of the real world situation into mathematical terms, it goes under generic name of mathematical modelling.

“Mathematical modelling is an activity which requires rather more than the ability just to solve complex sets of equations difficult through this may be”.

Mathematical modelling utilizes ANALOGY to help understand the behavior of complex system.

What is physical modelling?

In physical modelling nature is simulated on a smaller scale in the laboratory by a physical experiment.

When detailed mathematical models and/ or experimental field measurements become very costly, laboratory simulation using scaled down models in wind tunnels or water channels is often the best approach.

Concept of mathematical modelling applied to air pollution

Source : Point, Line, Area.Receptors : Humans.Transport : Decides fate of air pollutionRe-entertainment : Re suspension of air pollutants.

Air Quality Models

Analogy - helps in explaining / understanding unfamiliar situations.

Ex: Children playing father/ mother game Expectant mothers: practice nappy changing on dolls.

Models

-Not exact replica but contain some of nature’s essential elements.-Ex: When expectant mother practice nappy changing to dolls, dolls are laying still while in reality, babies do not lie still!. -Hence, models reflects a mathematical description of hypothesis conveying the behavior of some physical process or other.

What is air quality model A mathematical relationship between emissions and air quality that incorporates the transport, dispersion and transformation of compounds emitted into the air.

Model objective

Models are not a unique representation as they never completely replicate a system.

But models are useful tool in the design of new, large or otherwise modified existing processes or systems.

Conventional method of designing physical models replicating a process or system is time consuming and cumbersome process.

Physical models sometime can not replicate a system which is having complicated heat and mass transfer processes.

Mathematical models therefore is able to cope reasonably well with such processes or systems provided each is built into the set of mathematical equations.

Model categories

Suggested readings:

M. Crossal A.O. Moscardini, “Learning art of mathematical modelling”,Ellis Harmood Publication

Air Quality Models

Suggested readings:

Weber, E., “Air pollution assessment modelling methodology”, NATO, challenges of modern society, vol.2, Plenum press, 1982

What is deterministic approach?

The deterministic mathematical models calculate the pollutant concentrations from emission inventory and meteorological variables according to the solution of various equations that represent the relevant physical processes.

Deterministic modelling is the traditional approach for the prediction of air pollutant concentrations in urban areas.

Deterministic approach: Basics

What is Transport ?o It is also termed as advectiono Most obvious effect of atmosphere on emission

o Advection: implies transport of pollutant downwind of source

 

What is Dilution?o It is also termed as “mixing”.o It is accomplished through “turbulence”

o Mainly atmospheric turbulence is active

What is Dispersion?Dispersion = Advection (Transport) + Dilution = Advection +Diffusion

Basic Mathematical Equation

Deterministic based AQM

The deterministic based air quality model is developed by relating the rate of change of pollutant concentration in terms of average wind and turbulent diffusion which, in turn, is derived from the mass conservation principle.

where C = pollutant concentration; t = time; x, y, z = position of the receptor relative to the source; u, v, w =wind speed coordinate in x, y and z direction; Kx, Ky, Kz = coefficients of turbulent diffusion in x, y and z direction; Q = source strength; R = sink (changes caused by chemical reaction).

The above diffusion equation is derived in several ways under different set of assumptions for development of air quality models

Gaussian model is one of the mostly used air quality model based on ‘deterministic principle’

Reference:

Cheremisinoff, P.N.,1989. Encyclopedia of environmental control technology: air pollution control. Volume 2, Gulf Publishing Company, Houston.

Gaussian plume Dispersion model: Assumptions

Steady-state conditions, which imply that the rate of emission from the point source is constant. Homogeneous flow, which implies that the wind speed is constant both in time and with height (wind

direction shear is not considered).

Pollutant is conservative and no gravity fallout.

Perfect reflection of the plume at the underlying surface, i.e. no ground absorption.

The turbulent diffusion in the x-direction is neglected relative to advection in the transport direction , which implies that the model should be applied for average wind speeds of more than 1 m/s (> 1 m/s).

The coordinate system is directed with its x-axis into the direction of the flow, and the v (lateral) and w (vertical) components of the time averaged wind vector are set to zero.

The terrain underlying the plume is flat

All variables are ensemble averaged, which implies long-term averaging with stationary conditions.

Gaussian Plume Dispersion Model

Application: Gaussian Based Vehicular Pollutant Dispersion ModelThe basic approach for development of deterministic vehicular pollution (line source) model is the coordinate transformation between wind coordinate system (X1, Y1, Z1) andline source coordinate system (X, Y, Z).

A hypothetical line source is assumed to exist along Y1 that makes the wind direction perpendicular to it (Figure 1). The concentration at receptor is given by Csanady (1972):

Reference:

Csanday, G.T., 1972. Crosswind shear effects on atmospheric diffusion. Atmospheric Environment, 6,221-232.

Numerical approach

Numerical models also comes under deterministic modelling technique which are based on numerical approximation of partial differential equations representing atmospheric dispersion phenomena.

Basic mathematical equation

The term Ft in the above equation is unknown and diffused equation is not in close form.

Reference

Juda, K., 1986. Modelling of the air pollution in the Cracow area. Atmospheric Environment, 20 (12), 2449-2458.

Basis for numerical approach

First order closure models, also called K- models, have their common roots in the atmospheric diffusion equation derived by using a K-theory approximation for the closure of the turbulent diffusion equation. The first order closure models are time dependent.

Numerical based AQM

Eulerian grid model (Danard, M.B., 1972)Lagrangian trajectory model (Johnson, 1981)Hybrid of eulerian-lagrangian model (Particle-in-cell) (Sklarew et al., 1972)Random walk (Monte-Carlo) trajectory particle model (Joynt and Blackman, 1976)

Mostly used numerical based AQM

Gaussian puff model (Hanna et al., 1982)

Reference

Danard, M.B., 1972. Numerical modelling of carbon monoxide concentration near a Highway. Journal of Applied Meteorology, 11, 947-957.

Johnson, W.B., 1981. Interregional exchanges of air pollution: model types and application. In Air pollution modelling and its application-I, Edited by Wispelaere, C. De., Plenum Press, New York.

Sklarew, R.C., Fabrick, A.J. and Prager, J.E., 1972. Mathematical modelling of photochemical smog the using PIC method. Journal of Air Pollution Control Association, 22, 865-

Joynt, R.C. and Blackman, D.R., 1976. A numerical model of pollutant transport. Atmospheric Environment, 10, 433-.

Hanna, S.R., Brigs, G.A. and Hosker, Jr. R.P., 1982. Handbook on atmospheric diffusion. National Technical Information Centre, U.S. Department of Energy, Virginia.

Statistical Approach

Statistical models calculate pollutant concentrations by statistical methods from meteorological and emission parameters after an appropriate statistical relationship has been obtained empirically from measured concentration

Basis for statistical approach

Regression and multiple regression models (Comrie, 1997)

Regression models describes the relationship between predictors (meteorological and emission parameters) and predictant (pollutant concentrations)

Time series models (Box and Jenkins, 1976)

Time series analysis is purely based on statistical method applicable to non repeatable experiments. Box-Jenkins approach extracts all the trends and serial correlations among the air quality data until only a

sequence of white noise (shock) remains.

The extraction is accomplished via the difference, autoregressive and moving average operators.

Reference:

Comrie, A. C., 1997. Comparing neural networks and regression model for ozone forecasting. Journal of Air and Waste Management Association, 47, 653-663

Box, G.E.P. and Jenkins, G.M., 1976. Time series analysis forecasting and control. 2nd Edition, Holdenday, San Francisco.

Basic mathematical equation

The Box –Jenkins (B-J) models are empirical models created from the historical data.

Statistical graphs of the autocorrelation function (ACF) and partial autocorrelation function (PACF) to identify an appropriate time series model.

The general class of univariate B-J seasonal models, denoted by ARIMA (p, d, q) X ( P, D, Q)s can be expressed as:

Where = regular and seasonal autoregressive parameters, B = backward shift operators, =difference

operators, d and D = order of regular and seasonal differencing, s= period/span, = observed data series,

= regular and seasonal moving average parameters, at = random noise, p, P, q and Q represent the order of the model and c = constant.

Mostly used stochastic based AQM

- 24 h avg.. CO model- Max. daily 1-h avg.CO model - Max. daily working hours(8 AM - 8PM) 1-hour COmodel- Hourly average CO model

- 24 h avg.. CO model with wind speed as input- 24 h avg.. CO model with temperature as input- Max. daily 1-h avg.. CO model with wind speed as input- Max. daily 1-h avg.. CO model with temperature as input- Max. daily working hours 1-hour avg.. CO model with wind speed as input- Max. daily working hours1-hour avg.. CO model with temperature as input- Hourly average CO model withwind speed as input- Hourly average CO model with temperature as input

- 24 h avg.. CO model with temperature and wind speed as inputs - Max. daily 1-h avg.. CO model with wind speed and temperature as inputs - Max. daily working hours 1-hour avg.. CO model with wind speed and temperature as inputs

Reference:

Khare, M. and Sharma, P., 2002. Modelling urban vehicle emissions. WIT press, Southampton, UK. Sharma, P. and Khare, M., 2001. Short-time, real – time prediction of extreme ambient carbon monoxide

concentrations due to vehicular exhaust emissions using transfer function noise models. Transportation Research D6, 141-146.

Physical modelling approach – Wind Tunnel

26 m long, suction type, low wind speed, 16 m test section, 8 panels, 2 m each

 

EWT consists of entrance section, honeycomb section, wire mesh screen filters, test section, exit contraction section, transition and diffuser section 

Turntable of 1.8 m diameter 

Plenum chamber for prevention of surge and other disturbances, 6 m x 5 m wall

  ENVIRONMENTAL WIND TUNNEL- IIT DELHI

Basis for physical approach The physical simulation studies using wind tunnels have shown high potential to understand complex

urban dispersion phenomenon. The pollutant concentrations measured within the physical model can be converted to equivalent

atmospheric concentrations through the use of appropriate scaling relationship.

In the physical simulation studies of exhaust dispersion, the model vehicle movement system (MVMS) plays a vital role. The vehicle-induced turbulence can be understood accurately by using MVMS.

Design consideration for MVMS*

maintenance of ‘‘no slip’’ boundary condition in atmospheric boundary layer (ABL) flow,

variations in traffic volume and traffic speed for two-way traffic,

operation of MVMS for various street configurations,

variation in approaching wind directions and wind speed,

operation of vehicles in different lanes.

Reference:

*Ahmad, K., Khare, M. and Chaudhry, K.K. 2005. Wind tunnel simulation studies on dispersion at urban street canyons and intersections- a review. Journal of Wind Engineering and Industrial Aerodynamics, 93, 697-71

Eskridge, R.E. and Hunt, J.C.R., 1979. Highway modelling-I: prediction of velocity and turbulence fields in the wake of vehicles. Journal of Applied Meteorology, 18 (4), 387- 400.

Plan of MVMS for urban street

Plan of MVMS for Urban Intersection

Wind tunnel based AQM

Development, testing and validation of atmospheric dispersion models through EWT generated database in a variety of atmospheric conditions.

Systematic understanding of the pollutants dispersion characteristics for line source (automobile exhaust emissions), point source (stack emissions) and area source (low level areal emissions) in plain and complex terrains, such as, hills and valleys.

Understanding of the dispersive behavior of toxic gases from accidental releases.

Studies on the effects of pollutants on plants and buildings under dynamic environmental conditions for various geographical conditions.

Simulation of ‘heat islands’ and its effect on pollutant dispersion.

Location of ‘hot spots’ at the urban intersections.

Reference Eskridge, P.E. and Thompson, R.S., 1982. Experimental and theoretical study of the wake of a block-

shaped vehicle in a shear-free boundary flow. Atmospheric Environment, 16 (12), 2821-2836.

Snyder, W.H., 1972. Fluid models for the study of air pollution meteorology: similarity facilities, review of literature and recommendations, U.S. Environmental Protection Agency, Washington.

Limitations of Models *

Deterministic models Inadequate dispersion parameters Inadequate treatment of dispersion upwind of the road

Requires a cumbersome numerical integration especially when the wind forms a small angle with the roadways.

Gaussian based plume models perform poorly when wind speeds are less than 1m/s.

Numerical models have common limitations arising from employing the K-theory for the closure of diffusion equation. The K-theory diffusion equation is valid only if the size of the ‘plume’ or ‘puff’ of pollutants is greater than the size of the dominant turbulent eddies.

The Gaussian puff model relative diffusion parameters are derived from very few field experiments, which limits its applicability.

The other limitations of numerical models are large computational costs in terms of time and storage of data. It also requires large amounts of input data.

Statistical models Require long historical data sets and lack of physical interpretation. Regression modelling often underperforms when used to model non-linear systems.

Time series modelling requires considerable knowledge in time series statistics i.e. autocorrelation function (ACF) and partial auto correlation function (PACF) to identify an appropriate air quality model.

Statistical models are site specific.

Hybrid model prediction accuracy depends on the selection of suitable deterministic model and identification of appropriate statistical distribution parameter.

Application of hybrid approach to strongly auto correlated and/or non-stationary data requires specific treatment for auto correlation /non stationary to increase prediction accuracy.

In ANN based vehicular pollution model, the main problem facing when training neural network model, is deciding upon the network architecture (i.e., number of hidden layers, number of nodes in hidden layers and their interconnection).

At present, no procedures has been established for selecting proper network architecture, rather than training several network architecture and choose the best out of them.

Multilayer neural network performs well when used for interpolation, but poorly, if used for extrapolation.

No thumb rules exist in selection of data set for training, testing and validation of neural network based model.

Physical models: wind tunnel The major limitations of wind tunnel studies are construction and operational cost. Simulation of real time air pollution dispersion is expensive.

Real time forecast is not possible.

* Reference: Juda, K., 1989. Air pollution modelling. In: Cheremisinoff, P.N. (Eds.), Encyclopedia of Environmental

Control Technology, Vol. 2: Air Pollution Control, Gulf Publishing Company, Houston, Texas, USA, pp.83-134.

Nagendra, S.M.S. and Khare, M., 2002. Line source emission modelling- review. Atmospheric Environment, 36 (13), 2083-2098.

Box Model

Application : Area source

Principle :

(i) It assumes uniform mixing throughout the volume of a three dimensional box.

(ii) Steady state emission and atmospheric conditions.

(iii) No upwind background concentration.

Model description

Suggested reading:

Lyons, T.J. and Scott, W.D. “Principles of air pollution meteorology”, Behavan press,

1990

Line source model

Application

motor vehicle travelling along a straight section of highway OR agricultural burning along the edge of a fieldOR line of industrial sources on the bank of a river

Assumption

Infinite length source continuously emitting the pollution Ground level source

Wind blowing perpendicular to the line source

Model:

Indoor Air Pollution

A Common Myth

Air pollution occurs only outdoors Or In industrial environment

Truth!!!!

What is more agreeable than one’s home?Feeling safe ?Away from outside pollution ?

Air inside the conditioned space can be substantially more polluted than outdoor air.

Historical Perspective

First indication of indoor contamination – Asbestos pollution, a carcinogenic substance, discovered by epidemiologists, used in almost all building materials about 35 years back.Banned due to adverse health effects NOT considering IAQ.

Concept of IAQ first introduced among scientific community in 1980 due to some occurrences of ‘episodes indoors’.

At central headquarters of EPA building at Washington, D.C.- more than 100 people fell sick within 15 minutes of entering the office.In Los Angeles, CO level in most of the well insulated buildings was three times greater than the outside level.

Outcome

Such episodes indoors in developed nations ended up with

1. Extensive monitoring programme development indoors2. Identification of indoor contaminants3. Formulation of IAQ models4. Development of control methodologies5. Formulation of Indoor Air Contamination Standards.6. Identification of ‘Sick Buildings’7. Investigation of ‘Sick Building Syndrome(SBS)’

What is IAQ??

IAQ stands for “Indoor Air Quality” It refers to the nature of the conditioned (heat/ cool) air that circulates throughout space/area, where we work and live i.e. the air we breathe most of the time (almost 80 % of the time).

What Causes Indoor Air Pollution??

Air tightness of buildings Poorly designed air conditioning and ventilation systems Indoor sources of pollution Outdoor sources of pollution

Air Tightness in Buildings

Causes inadequate supply of fresh air, as a result, negative pressure develops, which causes

Ground level pollutants, e.g. CO, Radon etc.to be drawn inside the buildings. Release of odor (Bioaerosols) and other pollutants. Pull outside polluted air from vents, cracks and openings and increase dust, pollen etc. Causes “Sick Building Syndrome”.

Poorly Designed Air Conditioning Systems

Results into the production of fungi, molds and other sickness causing microbes.

Problems of IAQ

Enclosed spaces inhabited by humans produce following effects-

Reduction in oxygen level of spaces.

Increase in CO2 level. Increase in temperature. Increase in humidity Increase in Bioaerosols and odor

Sources of Indoor Air Pollution in a Typical Office Building

Sources of Indoor Air Pollution in a Typical Household

Hard Facts

Fresh air contains 21.0% (v/v) O2 Exhaled air contains 17.0% (v/v) O2 and 83.0 % (v/v) CO2 An adult emits 45 gm sweat / hour containing bioaerosols. An adult produces 300 BTU of heat / hour. Carbon based gaseous pollutants (VOCs) indoors are 2 to 5 times higher than outdoors.

Poor IAQ Results

Indoor Air Pollutants and Their Health Effects

Pollutant Effect Limits

NOzType: ImmediateCauses: irritation to the skin, eyes and throat, cough etc.

0.05 ppm (avg. over one year for 8 hours exposure daily)- EPA

CO

Type: ImmediateCauses: headache, shortness of breath, higher conc. May cause sudden deaths..

9.0 ppm (avg. over 8 hours period)- EPA

RSPMType: CumulativeCauses: Lung cancer

150 µg/ m3 (24 hr. average)

SO2Type: ImmediateCauses: lung disorders and shortness of breath

0.05 ppm (avg. over one year for 8 hours exposure daily)- EPA

Radon Type: CumulativeCauses: Lung cancer

>/ 4 pCi/ Litre of indoor air

Formaldehyde Type: ImmediateCauses: irritation to the eyes, nose and throat, fatigue, headache, skin allergies, vomiting etc.

120 ? g/ cu.m. (continuous exposure)- ASHRAE

Asbestos Type: CumulativeCauses: Lung cancer

>/ 2 fibers/ cu.cm. Of the indoor air (8 hrs. exposure period)- OSHA

PesticidesType: ImmediateCauses: Skin diseases

 

VOCsType: ImmediateCauses: Liver, kidney disorders, irritation to the eyes, nose and throat, skin rashes and respiratory problems.

Not for all VOCs. For chlordane: 5? g/cu.m.(continuous exposure))

CO2 Surrogate index of ventilation 1000 ppmO3 Type: Immediate

Causes: eyes itch, burn, respiratory disorders, lowers our 100 ? g/cu.m (continuous exposure)- OSHA

resistance to colds and pneumonia.

WHO Standards

PollutantsConcentration reported

Concentrations of limited or no concern

Concentration of concern

Remarks

Respirable particulates

0.05 – 0.7 <0.1 >0.015 Japanese standard 0.15 mg/cubic m

CO1-1.5 <2 >5 Indicator for eye

irritation(only from passive smoking)

NO2 0.05 – 1 <0.19 >0.32 ------

CO---- 2% CO Hb 3%COHb 99.9%

1-100 < 11 >30Continuous exposure

Formaldehyde 0.05 – 2 < 0.06 >0.12Long- and Short- term

SO2 0.02 – 1 < 0.5 >1.35SO2 alone, short-term

CO2 500 – 5000 ppm < 1000 ppm >1000 ppmOccupancy indicator

O3 600-9000 < 1800 >12000 Japanese standard 1800 mg/cubic m

  <10 fibres/cubic m ~ 0 fibre/m For long Exposure

* typical ranges of concentration is given in mg/cubic m, unless otherwise indicated

Parameters Affecting IAQ

Rate of exchange of air from outdoors (ventilation) Concentration of pollutants in outdoor air Rate of emission from sources indoors Rate of removal of pollutants (Sinks) Indoor temperature Indoor humidity Age of indoor structure Type of foundation soil

Steps for Investigating IAQ Problems

Document employee health complaints. Examine floor plans and ventilation system specifications. Analysis of data collected from above steps for SBS score calculations. Study of building layout, position and location of windows, doors, vents, openings etc. Ventilation measurement. Monitoring of indoor pollutants and other environmental parameters and development of IAQ model. Develop a plan for reducing and eliminating the IAQ problem

What is Ventilation??

A process, whereby air is supplied and removed from an indoor space by natural or mechanical means.

Why ventilation is needed indoors?

To remove heat or moisture OR to reduce the concentration of one OR more indoor pollutants

Types of Ventilation Natural Mechanical

Natural Ventilation Involves Infiltration: random/ intentional flow of outdoor air through windows, cracks and a variety of openings in the buildings.Exfiltration: movement of air from indoor spaces to outdoor.

Limitation of Natural Ventilation Fairly inefficient as it is NOT UNIFORMLY distributed. Air doesn’t circulate evenly and stale air gets

collected in some dead end spaces. It brings POLLENS & OTHER POLLUTANTS from outside air.

Maximum energy loss occurs as NO CONSERVATION of energy can be done

Mechanical ventilation

It involves use of fans and heating / air conditioning equipments.

Principle of mechanical ventilation

Pulling fresh air from outside to indoor spaces. Exhaust stale air.

Control temperature and humidity inside.

Ventilation Measurement

A. In naturally ventilated buildings

By Infiltration measurement.Infiltration is reported as air change per hour (ACH) – the average rate at which indoor air is replaced by fresh outdoor air.ACH is a rough guideline for different building conditions, given by ASHRAE. For e.g., in “air tight buildings” ACH is 0.1 to 0.2, in “leaky building”, ACH is 2.0 to 3.0. ASHRAE model for measuring infiltration in naturally ventilated buildings is –I = ln (CO / Ci) / t

Tracer gas technique is employed to measure infiltration. Non reactive gases, e.g. SF6/NO are used as tracer gases with the assumption that the loss of tracer gas is only due to ventilation/ exfiltration.

B. In mechanically ventilated buildings

ACH is measured by CO2 concentration. It is a good surrogate index to determine the proper ventilation in HVAC buildings. ASHRAE model for measuring infiltration in HVAC buildings is –Q = G/ Ci – Ca

Minimum recommended ventilation rate by ASHRAE is 8L/sec. per person to maintain the indoor concentration of CO2 as 700 ppm.

Parameters for Natural Ventilation

Air Flow- occurs mainly due to two driving forces

1. Pressure Gradient – Difference in outdoor and indoor pressure (varies with building shape, size, openings, wind direction, local environmental densities, neighbour building’s configuration, topography etc.)

2. Temperature Gradient (Buoyancy Forces)- when the inside air temperature is higher than outside air, the warm air at floor surface starts rising and the cool air starts entering as a result of vaccum created at floor surface. This effect is called as “Stack Effect”.

Parameters for Mechanical Ventilation Infiltration air Exfiltration air

Recirculated air

Exhaust air

Makeup air

What is sick building syndrome?

The feeling of illness among majority of occupants of a conditioned space is called “Sick Building Syndrome”. A variety of illness symptoms reported by occupants in sick buildings are – Headache, fatigue, irritation in eyes, nose and throat, shortness of breathe etc.

Causes

Inadequate ventilation – insufficient supply of outside air; poor mixing; fluctuations in temperature & humidity; air filtration problem due to lack of maintenance of HVAC systems.

The CO2 level indicates the ventilation efficiency of buildings. Building shows SBS symptoms, if CO2 concentration > 1000 ppm.

About The building1. How old is the building?

2. What construction materials have been used?

3. How many floors in the building? How many square feet per floor?

4. What types of windows are in the building? Do they open?

5. Who is responsible for the functioning of the building systems?

6. Who is responsible for cleaning the interior of the building? How often is the building cleaned?

7. Have there been any major renovations or operating changes ? What are they ? When did they occur?

8. Does the building have sprayed or foamed insulation? When was it applied?

9. What type of heating system is used?

10. What type of cooling system is used?

11. What type of humidification system is used?

12. How is the total ventilation system operated?

13. What floors and rooms are served by each system?

14. What type of filtration system is used? How often it is changed or maintenainced?

15. How much fresh air is being introduced into the ventilation system? Does this amount meet system specifications?

16. Where are the fresh air inlets? Are they functioning properly?

17. Are there any possible sources of contamination located in the general vicinity of the air inlets?

18. How likely are contaminants to be drawn into the air inlets due to prevailing winds and inversions?

19. How does exhaust air leave the building?

20. Is the building being used for the same purpose for which it was designed?

21. What type of activities are buliding occupants engaged in?

22. What processes or activities are present in the building that may serve as contaminant sources?Is locla exhaust ventilation used near contamination sources?

Employees Questionnaire1. What health complaints have experienced at work?

2. Do you have any of the following conditions?Hey fever _______Other allergies ________Dermatitis or other skin problems______Sinus problems______Cold or Flu______Naussea or dizziness____Eye irritation________Headache______Excess fatigue______Joint aches_____

3. When did you first noticed these symptoms?

4. When do the symptoms occur? How often?

5. Do your symptoms clear within an hour of leaving work?If not, which symptoms persist through the week?

6. Are the symptoms more likely to appear at particular times of day?

7. Do they occur in the particular areas of the building?

8. How many co-workers smoke? Do they smoke?

9. Is there a specific incident to which your health problems can be traced( ie building renovations, installation of new carpets,purchase of new furniture)

10. What office machines are used in your vicinity? What chemicals do they use?

11. What office products are used that contain chemicals?List the ingredients?

12. What fabrics are used in the carpets,curtains, shades and wall coverings? Is there any evidence of excessive dust or mold?

13. Are you aware of any water leakage that have not been repaired so far?

14. What is your overall assessment for the air quality and confort level in your office?

15. Do you work with any office equipment? Specify the type?

16. Where is your office located? Specify floor, department, and proximity to office equipment ?

17. How old are you?

18. What is your job title? Briefly describe your responsibilties?

19. Whta is the general condition of your health?

20. Is there any family histroy or illness?

Indoor Air Quality Modelling

Monitoring and modelling of indoor air pollutants

Parameters considered are Temporal variation of indoor air pollutants. Spatial variations of indoor air pollutants.

Chemical transformation of pollutants.

Population inside the indoor space.

Outdoor pollutant concentration.

Indoor-outdoor air exchange rate (ventilation).

ndoor air pollutant sources.

Indoor air pollutant sinks.

Sampling techniques

Quite complicated as normal routine of users of the building should not be disturbed. Continuous sampling is preferred instead of grab sampling. Meteorological data inside and outside the building are need to be collected

Outdoor concentration of relevant pollutants are also needs to be collected.

Modelling of IAQ

Role of IAQM Relates indoor pollutants concentration to various geometric,ventilation, source and sink parameters. Predict peak concentration or dosage indoors as a function of outdoor air pollutant concentrations and

indoor- outdoor air exchange rate.

IAQ Model Development

A statement of the mass balance concerning pollutant of interest in an indoor space.Parameters for mass balance statement

Concentration of pollutant, C. Volume of indoor space, V.

Flow rate of fresh make up air from outside through filter, q0

Flow rate of building air recirculated through another filter, q1

Infiltration rate of outside air through openings, q2

Filter factor, F which is defined as below

:

Types of IAQ models

Single compartment model

Used, when; Rate of mixing is uniform throughout the region. Sources and sinks are uniformly distributed.

Multi compartment model

Used, when; Rate of mixing is low compared with the characteristic residence time of the pollutants. Sources and sinks are NOT uniformly distributed.

IAQ Mass Balance Model

The basic mass balance equation, on which the compartmental modelling technique is based is

Rate of increase of pollutant conc. = Rate of pollutant entering - (Rate of pollutant leaving + Rate of accumulation + Source + decay rate)

RESEARCH STUDIES AT IIT DELHI

1994 - onwards…

Evaluating indoor air quality using CO2 as surrogate index (J. AIRAH, Vol. 51, No.11, 1997, Australia)

Sites investigated

IIT Delhi – Central Library, Inorganic Chemistry Research Laboratory, Physical Chemistry Laboratory, IC Engine Laboratory.

Indoor Parameters Monitored – CO2, NO2, SO2, TSP.

Instrumentation – Handy samplers, Low Volume Samplers

Findings- Prevalence of ‘Stack Effect’ for CO2- Evening Concentration of CO2 > day concentration- Settlement of Gases towards the floor after closure of the buildings- Improper mixing and dispersion at upper floor levels- CO2 concentration is a function of window area/ occupant and window area / unit floor area rather than on total window area. Maximum CO2 concentration 500 mg/ cu.m

Sick Building Syndrome in an Educational Institute Library and Laboratories (in 7th International Conference on Indoor Air Quality & Climate, Vol. 4, pp 269-74, 1996)

Sites investigated IIT Delhi – Central Library, Inorganic Chemistry Research Laboratory, Physical Chemistry Laboratory, IC Engine Laboratory.

Population studies – 130 (at all the four sites)Sampling Technique – Grab samplingSBS Scale – 0.0 -1.0 ( 0.0 = often; 0.5 sometimes; 1.0 never)Indoor Parameters Monitored – CO2, NO2, SO2, TSP, SBSInstrumentation – Handy samplers, Low Volume SamplersFindings

- SBS score is a decisive parameter in IAQ study.- Prevalence (%) of SBS symptoms in Central Library- Irritation in eyes 10% of total population - often; - Irritation in nose 14% of total population- ‘often’;- Dryness in mucous 28% of total population- ‘often’.- lethargic / drowsy 38% of total population – ‘often’- Dryness 18% of total population – ‘often’, 100% at labs – ‘often’- Headache 17% of total population – ‘often’ 100% at labs – ‘often’

Indoor air quality in centrally air- conditioned airport authority building (MS research thesis, 1999)

Sites investigated - airport authority office complex Sampling Technique – Grab sampling

SBS Scale – 0.0 - 4.0 ( usually; often; sometimes)Indoor Parameters Monitored – SPM, CO2, NO2, SO2, CO and SBSInstrumentation – IAQ monitor, Handy samplers, Findings –Correlation was found between CO2 concentration and % outdoor intake. –the recirculated air increased the CO2 concentration on 2nd and 3rd floor.– SBS score was found on 3rd floor is 3.01, which is higher than other floors – stack effect was observed in the building.–sudden increase in occupancy level on ground floor resulted in increase in CO2 concentration.– Females were more susceptible to SBS symptoms as compared to men and occupants in the age group of 20-29.– direct relation between CO2 concentration and SBS Score shows that SBS score is a useful indicator of IAQ - Insufficient supply of make-up (fresh) air was found in the building.

Environmental evaluation of a public building with respect to IAQ (sponsored research project by MHRD, 2000- 2001)

Site Investigated – Departure terminal- IGI Airport Sampling Technique – integrated and continuousIndoor Parameters Monitored – RSPM,SPM, CO2, NO2, SO2, CO and SBSMeteorological Parameters– temperature, humidity, wind velocity and wind directionInstrumentation – IAQ monitor, Handy samplers, Bioaerosol sampler, airflow meter, weather stationFindings– Pollutant concentration were found within the limits except CO2 concentration, which was very high in peak hours

(nights and weekends)– SBS score indicated the building as ‘Sick’– Insufficient supply of make up (fresh ) air in the building caused negative pressure inside the building w.r.t. outdoor pressure.– I/O showed that the high concentration of pollutant inside is due to possible penetration of outside air.

IAQ monitoring at offices/ commercial complexes (post doctoral research, sponsored by DST, 2001-2003)

Site Investigated – Centrally air conditioned multistory commercial buildingSampling Technique – integrated and continuousIndoor Parameters Monitored – RSPM,SPM,CO2, NO2, SO2, CO, O3 and BioaerosolsMeteorological Parameters – temperature, humidity, wind velocity and wind directionInstrumentation – IAQ monitor, Handy samplers, Bioaerosol sampler, HVS, air flow meter, weather station, ozone test stripsFindings – Insufficient ventilation– 100 percent recycled air.– High concentration of CO2 in corridors of all floors.

IAQ monitoring studies in naturally ventilated school buildings (Ongoing PhD)

Sites Selected - A naturally ventilated three storied school building in South Delhi Indoor Parameters Monitored – RSPM, CO2, NO2, SO2, CO and ventilation parametersInstrumentation – IAQ monitor, Handy samplers, Differential pressure manometers, Dust monitor, Environmental Wind Tunnel (EWT) Wind Tunnel simulation of building for measuring pressure coefficient (Cp) and air flow pattern in and around the building at different orientation of wind and different opening conditions.

Expected Findings– the relationship between ventilation and the IAQ – Formulation of IAQ model for naturally ventilated building – I/O relationship – SBS – Validation of aerodynamics using wind tunnel in a naturally ventilated building

Indoor Air Quality Modelling

Monitoring and modelling of indoor air pollutants

Parameters considered are Temporal variation of indoor air pollutants. Spatial variations of indoor air pollutants.

Chemical transformation of pollutants.

Population inside the indoor space.

Outdoor pollutant concentration.

Indoor-outdoor air exchange rate (ventilation).

ndoor air pollutant sources.

Indoor air pollutant sinks.

Sampling techniques

Quite complicated as normal routine of users of the building should not be disturbed. Continuous sampling is preferred instead of grab sampling. Meteorological data inside and outside the building are need to be collected

Outdoor concentration of relevant pollutants are also needs to be collected.

Modelling of IAQ

Role of IAQM Relates indoor pollutants concentration to various geometric,ventilation, source and sink parameters. Predict peak concentration or dosage indoors as a function of outdoor air pollutant concentrations and

indoor- outdoor air exchange rate.

IAQ Model Development

A statement of the mass balance concerning pollutant of interest in an indoor space.Parameters for mass balance statement

Concentration of pollutant, C.

Volume of indoor space, V.

Flow rate of fresh make up air from outside through filter, q0

Flow rate of building air recirculated through another filter, q1

Infiltration rate of outside air through openings, q2

Filter factor, F which is defined as below

:

Types of IAQ models

Single compartment model

Used, when; Rate of mixing is uniform throughout the region. Sources and sinks are uniformly distributed.

Multi compartment model

Used, when; Rate of mixing is low compared with the characteristic residence time of the pollutants. Sources and sinks are NOT uniformly distributed.

IAQ Mass Balance Model

The basic mass balance equation, on which the compartmental modelling technique is based is

Rate of increase of pollutant conc. = Rate of pollutant entering - (Rate of pollutant leaving + Rate of accumulation + Source + decay rate)

RESEARCH STUDIES AT IIT DELHI

1994 - onwards…

Evaluating indoor air quality using CO2 as surrogate index (J. AIRAH, Vol. 51, No.11, 1997, Australia)

Sites investigated

IIT Delhi – Central Library, Inorganic Chemistry Research Laboratory, Physical Chemistry Laboratory, IC Engine Laboratory.

Indoor Parameters Monitored – CO2, NO2, SO2, TSP.

Instrumentation – Handy samplers, Low Volume Samplers

Findings- Prevalence of ‘Stack Effect’ for CO2- Evening Concentration of CO2 > day concentration- Settlement of Gases towards the floor after closure of the buildings- Improper mixing and dispersion at upper floor levels- CO2 concentration is a function of window area/ occupant and window area / unit floor area rather than on total window area. Maximum CO2 concentration 500 mg/ cu.m

Sick Building Syndrome in an Educational Institute Library and Laboratories (in 7th International Conference on Indoor Air Quality & Climate, Vol. 4, pp 269-74, 1996)

Sites investigated IIT Delhi – Central Library, Inorganic Chemistry Research Laboratory, Physical Chemistry Laboratory, IC Engine Laboratory.

Population studies – 130 (at all the four sites)Sampling Technique – Grab samplingSBS Scale – 0.0 -1.0 ( 0.0 = often; 0.5 sometimes; 1.0 never)Indoor Parameters Monitored – CO2, NO2, SO2, TSP, SBSInstrumentation – Handy samplers, Low Volume SamplersFindings

- SBS score is a decisive parameter in IAQ study.- Prevalence (%) of SBS symptoms in Central Library- Irritation in eyes 10% of total population - often; - Irritation in nose 14% of total population- ‘often’;- Dryness in mucous 28% of total population- ‘often’.- lethargic / drowsy 38% of total population – ‘often’- Dryness 18% of total population – ‘often’, 100% at labs – ‘often’- Headache 17% of total population – ‘often’ 100% at labs – ‘often’

Indoor air quality in centrally air- conditioned airport authority building (MS research thesis, 1999)

Sites investigated - airport authority office complex Sampling Technique – Grab sampling

SBS Scale – 0.0 - 4.0 ( usually; often; sometimes)Indoor Parameters Monitored – SPM, CO2, NO2, SO2, CO and SBSInstrumentation – IAQ monitor, Handy samplers, Findings –Correlation was found between CO2 concentration and % outdoor intake. –the recirculated air increased the CO2 concentration on 2nd and 3rd floor.– SBS score was found on 3rd floor is 3.01, which is higher than other floors – stack effect was observed in the building.–sudden increase in occupancy level on ground floor resulted in increase in CO2 concentration.– Females were more susceptible to SBS symptoms as compared to men and occupants in the age group of 20-29.– direct relation between CO2 concentration and SBS Score shows that SBS score is a useful indicator of IAQ - Insufficient supply of make-up (fresh) air was found in the building.

Environmental evaluation of a public building with respect to IAQ (sponsored research project by MHRD, 2000- 2001)

Site Investigated – Departure terminal- IGI Airport Sampling Technique – integrated and continuousIndoor Parameters Monitored – RSPM,SPM, CO2, NO2, SO2, CO and SBSMeteorological Parameters– temperature, humidity, wind velocity and wind directionInstrumentation – IAQ monitor, Handy samplers, Bioaerosol sampler, airflow meter, weather stationFindings– Pollutant concentration were found within the limits except CO2 concentration, which was very high in peak hours

(nights and weekends)– SBS score indicated the building as ‘Sick’– Insufficient supply of make up (fresh ) air in the building caused negative pressure inside the building w.r.t. outdoor pressure.– I/O showed that the high concentration of pollutant inside is due to possible penetration of outside air.

IAQ monitoring at offices/ commercial complexes (post doctoral research, sponsored by DST, 2001-2003)

Site Investigated – Centrally air conditioned multistory commercial buildingSampling Technique – integrated and continuousIndoor Parameters Monitored – RSPM,SPM,CO2, NO2, SO2, CO, O3 and BioaerosolsMeteorological Parameters – temperature, humidity, wind velocity and wind directionInstrumentation – IAQ monitor, Handy samplers, Bioaerosol sampler, HVS, air flow meter, weather station, ozone test stripsFindings – Insufficient ventilation– 100 percent recycled air.– High concentration of CO2 in corridors of all floors.

IAQ monitoring studies in naturally ventilated school buildings (Ongoing PhD)

Sites Selected - A naturally ventilated three storied school building in South Delhi Indoor Parameters Monitored – RSPM, CO2, NO2, SO2, CO and ventilation parametersInstrumentation – IAQ monitor, Handy samplers, Differential pressure manometers, Dust monitor, Environmental Wind Tunnel (EWT) Wind Tunnel simulation of building for measuring pressure coefficient (Cp) and air flow pattern in and around the building at different orientation of wind and different opening conditions.

Expected Findings– the relationship between ventilation and the IAQ – Formulation of IAQ model for naturally ventilated building – I/O relationship – SBS – Validation of aerodynamics using wind tunnel in a naturally ventilated building

Photochemical Smog

Photochemical smog ??

Noxious mixture of highly reactive and oxidizing air pollutants including:

Oxides of Nitrogen (NOx) Volatile organic compounds

Troposphere Ozone

Peroxyacetyl Nitrates (PAN)

Generation Mechanism

Three ingredients required:

Ultraviolet Light Hydrocarbons

Nitrogen oxides

Photochemical Reaction

 

Photochemical Reactions

1) Tropospheric Ozone:

Sources

Exhaust gases From Motor vehicles

Unburnt Hydrocarbons

2) Volatile Organic Compounds (VOC)

Carbon-based molecules such as Aldehydes,

Ketones and Hydrocarbons

Sources

Paint thinners, solvents and petroleum constituents Trees: emits isoprene and terpenes Methane from termites, cows and cultivation

 

3) Peroxyacetyl Nitrates (PAN)

Are secondary pollutants formed from peroxyacid radicals and NO2

Effects on human health

Ozone

- Cause acute respiratory problems - Aggravate asthma - Cause temporary decreases in lung function in healthy adults - Lead to hospital admissions and emergency room visits - Impair the body's immune system

 

Peroxyacetylnitrate (PANs)

- Respiratory and eye irritants- Mutagenic- causing skin cancer

Volatile organic compounds (VOCs) - Global warming- Methane- Carcinogenic- benzene- Form Ozone

Ozone problem

Introduction

That is, the layer of life-protecting ozone found at the top of the stratosphere. A brief history of the discovery of the ozone 'hole' is included. The general concepts found in this section include the following:

Concentrations of stratospheric ozone represent a balance, established over eons, between creative and destructive forces and this balance, or dynamic equilibrium, has been changed by human activity.

Ozone is formed in the earth's stratosphere and is critical to life on earth as we know it.

There is compelling scientific evidence that ozone is destroyed in the stratosphere and that some human-released chemicals are speeding up the breakdown of ozone in the atmosphere.

CFCs, a human-developed compound, are particularly destructive to the breakdown of ozone in the atmosphere.

Ultraviolet radiation is present in natural outdoor light and can be blocked or filtered by various substances.

Ozone Layer Depletion: Historical Perspective

The ozone 'hole', it is really not a hole but rather a thinning of the ozone layer in the stratosphere. We will use the term 'hole' in reference to the seasonal thinning of the ozone layer.

The appearance of a hole in the earth's ozone layer over Antarctica, first detected in 1976. 1974: Rowland & Molina theorize CFCs destroy stratospheric ozone molecules

1975: U of M / Harvard papers predict that CFCs deplete Earth’s ozone layer

1985: Ozone holes found over Antarctic

1988: Ozone layer thinning over North Pole

1993: Thinning over mid-latitudes of the Northern Hemisphere

1997: Low values of total ozone occur in Arctic as well as Antarctic

Antarctic Ozone Hole Progression

1979 1986 1991

 

CH4 itself is an important greenhouse gas, and links climate with air pollution via its influence on tropospheric ozone

CONTINENT 1 OCEAN CONTINENT 2

Ozone Layer Depleting Chemicals

chlorofluorocarbons (CFCs)carbon tetrachloride (CCl4)methyl chloroform (CH3CCl3)hydrochloric acid (HCl)methyl chloride (CH3Cl)methyl bromide(CH3Br)

International Response to Ozone Layer Depletion

1985: United Nations Environment Program (UNEP) 1987: The Montreal Protocol

1992: Copenhagen Amendments

1998: The Montreal Protocol is affecting stratospheric chemical composition.

International Response to Ozone Layer Depletion

1999-2000: Stratospheric ozone layer recovery will be a slow process and extend into the next century.Scientific Assessment of Ozone Depletion: 1994 and 1998 (World Meteorological Organization).Ozone Depletion Web Page: http://www.epa.gov/ozone

Ozone Layer Depleting Chemicals: Chlorine

 

Ozone Layer Depleting Chemicals: CFCs

CFCs are inert, nonreactive, nontoxic, nonflammable. Human-made CFCs used in:

- refrigeration- air conditioning- foam blowing- cleaning electronic components- solvents

CFC Reactions Deplete Ozone Layer in Stratosphere

Ozone Depleting Process

Global Stratospheric Ozone Layer Depletion Trend

Biological Effects of Ultraviolet Radiation

Sunburn,Premature Aging & PreCancer Cancer of Skin

-Basal and Squamous Cell Carcinoma-Melanoma

Cataracts

Photosensitivity

Immune system changes

Human Immune System can be suppressed by ultraviolet radiation

Human Immune System can be suppressed by ultraviolet radiation

Human Immune System can be suppressed by ultraviolet radiation

 

suppression of immune system increased incidence of infection

promotion of cancer growth

The Skin Cancer Epidemic

Basal cell carcinoma- most common, least aggressive, locally destructive

Squamous cell carcinoma- more aggressive, can metastasize

Melanoma- most aggressive, ~75% of all skin cancer deaths

The Skin Cancer Epidemic

melanoma is increasing in incidence faster than any other cancer lifetime probability of developing melanoma is 1 in 75

100 new cases of melanoma diagnosed per day, ~ one death per hour

The Skin Cancer Epidemic Problems

knowledge: 1/3 of Americans know that melanoma is a kind of skin cancer attitudes: >60% of Americans think people look better with a tan

behavior: only 1/4 of the population use sunscreens regularly

Cataracts of Eyes

cataracts are when the lens of the eye becomes cloudy 20 million cases worldwide

account for half of blindness in the world

Good & Bad Effects of Sunlight

 

 

References

“Environmental Effects of Ozone Depletion.” AMBIO 24 May(1995):137-196. Cook, Elizabeth, ed. Ozone Protection in the United States: Elements of Success. Washington, D.C.:

World Resources Institute,1996.

UNEP Ozone Depletion Report 1994/98 http://www.gcrio.org/ozone/toc.html http://www.gcrio.org/UNEP1998/

Southern Hemisphere Ozone Hole Size http://www.cpc.ncep.noaa.gov/products/stratosphere/sbuv2to/ozone_hole.html

Health and Environmental Effects of Ultraviolet Radiation. INTERSUN: The Global UV Project. 9 Sep 1998. http://www.who.int/peh-uv/publications/index.html

The health impact of solar radiation and prevention strategies. Report of the Environment Council, American Academy of Dermatology. J Am Acad Dermatol 1999; 41:81-99.

Think Globally and Act Locally

Acid Rain

What ever happened to acid rain?

In the 1980’s, acid rain received a lot of media attention. Although we don’t hear about acid rain as much these days, it is still a problem that deserves our attention. Fortunately, acid rain is a problem that we can all help to solve.

What is Acid Rain? How Does it Form?

Acid rain” includes both wet and dry acidic deposits Precipitation with a pH lower than 5.6 is considered acidic Acid rain originates from sulfur dioxide and nitrogen oxide particles Once these particles are emitted into the air they form sulfate and nitrate particles These particles can travel long distances on wind currents By combining with water vapor, these particles form acids which fall to the earth as acid rain.

The pH Scale

Measures Potential of Hydrogen= total # of free hydrogen

 

Where do Sulfur Dioxide & Nitrogen Oxide Particles Come From?

Sulfur dioxide and nitrogen dioxide particles are emitted from utility plants, especially coal-fed electric plants Automobiles also emit acid rain causing pollution

How Does Acid Rain Effect Our Lives?

Poor forest health due to acidification of soil: acid rain can kill nutrient-producing microorganisms Acidification of lakes and streams can lead to the death of aquatic life, such as trout and bass Acidity can leach mercury out of the soil, causing toxic levels to build up in the fish we eat

Acid rain can erode buildings and monuments and destroy paint finishes

What else needs to be done about Acid Rain ?

In 1990, an amendment to the Clean Air Act called for reductions in sulfur emissions This proved to be less effective than hoped, as acid rain still persists today This is largely due to 2 reasons: -1) reductions in sulfur emissions were not great enough and - 2) there were no reductions in nitrogen emissions which are also implicated in forming acid rain Presently, the New England Governors and eastern Canadian Premieres are working together on a solution An International Acid Rain Steering Committee was formed and is currently discussing joint action to further reduce sulfur emissions by 50% and reduce nitrogen emissions by 30% by the year 2010

Can We Do Anything About Acid Rain?

YES! We can all take small actions to help solve the problem We can help by:-using our cars less-conserving electricity -choosing electricity providers that emit lower amounts of air pollution emissions