The Atmosphereand

Air Pollution

a

Origin of Modern Atmosphere• original atmosphere surrounded the homogenous

planet Earth and probably was composed of H and He

• second atmosphere evolved from gases from molten Earth– H2O, CO2, SO2, CO, S2, Cl2, N2, H2, NH3, and CH4

– allowed formation of oceans and earliest life

• modern Atmosphere– evolved after Cyanobacteria started photosynthesizing

– oxygen produced did not reach modern levels until about 400 million years ago

• compared to the size of the Earth (104 km), the atmosphere is a thin shell (120 km).

Earth’s Atmosphere

http://www.gsfc.nasa.gov/gsfc/earth/pinatuboimages.htm

• Exosphere

• Thermosphere

• (Ionosphere)

• Mesosphere

• Stratosphere

• Troposphere

AtmosphereLayers

Troposphere

• 8 to 14.5 kilometers high (5 to 9 miles)• most dense• the temperature drops from about 17 to -

52 degrees Celsius• almost all weather is in this region

Stratosphere• extends to 50 kilometers (31 miles) high• dry and less dense• temperature in this region increases

gradually to -3 degrees Celsius, due to the absorption of ultraviolet radiation

• ozone layer absorbs and scatters the solar ultraviolet radiation

• ninety-nine percent of "air" is located in first two layers

• every 1000-m 11% less air pressure

Composition

• Nitrogen (N2, 78%)• Oxygen (O2, 21%)• Argon (Ar, 1%)• myriad of other very

influential components are also present which include the Water (H2O, 0 - 7%), "greenhouse" gases or Ozone (O3, 0 - 0.01%), Carbon Dioxide (CO2, 0.01-0.1%),

Importance of the Atmosphere

• Physicists – physical properties and processes that take

place between the radiant energy and atmospheric gases

• Chemists – behavior of the chemical materials in the

atmosphere• the ways in which lightning causes the

formation of substances • chemistry of the ozone layer and of chemicals

introduced from industrial processes

• Astronomers and space scientists – the layer through which they must peer

before entering the realms of space

• Meteorologists, climatologists and geographers– lower layers of the atmosphere

• predicting the weather• investigating climatic regions • examine the effects of climate and weather on

human society

Outdoor Air Pollution

Primary Pollutants

Secondary Pollutants

SourcesNatural

Stationary

CO CO2

SO2 NO NO2

Most hydrocarbons

Most suspendedparticles

SO3

HNO3 H2SO4

H2O2 O3 PANs

Most and saltsNO3–

Mobile

SO42–

Major Sources of Primary Pollutants

Stationary Sources• Combustion of fuels for power and heat – Power Plants• Other burning such as Wood & crop burning or forest

fires• Industrial/ commercial processes• Solvents and aerosols

Mobile Sources• Highway: cars, trucks, buses and motorcycles• Off-highway: aircraft, boats, locomotives, farm

equipment, RVs, construction machinery, and lawn mowers

54 million metric tons from mobile sources in 1990

Human Impact on Atmosphere• Burning Fossil Fuels

• Using Nitrogen fertilizers and burning fossil fuels

• Refining petroleum and burning fossil fuels

• Manufacturing

Adds CO2 and O3 to troposphere Global Warming Altering Climates Produces Acid Rain Releases NO, NO2, N2O, and NH3

into troposphere Produces acid rain Releases SO2 into troposphere

Releases toxic heavy metals (Pb, Cd, and As) into troposphere

www.dr4.cnrs.fr/gif-2000/ air/products.html

Criteria Air PollutantsEPA uses six "criteria pollutants" as indicators of air quality

1. Nitrogen Dioxide: NO2

2. Ozone: ground level O3

3. Carbon monoxide: CO4. Lead: Pb5. Particulate Matter: PM10 (PM 2.5)

6. Sulfur Dioxide: SO2

• Volatile Organic Compounds: (VOCs)

EPA established for each concentrations above which adverse effects on health may occur

Nitrogen Dioxide (NO2)• Properties: reddish brown gas, formed as

fuel burnt in car, strong oxidizing agent, forms Nitric acid in air

• Effects: acid rain, lung and heart problems, decreased visibility (yellow haze), suppresses plant growth

• Sources: fossil fuels combustion, power plants, forest fires, volcanoes, bacteria in soil

• Class: Nitrogen oxides (NOx) • EPA Standard: 0.053 ppm

Mobile Source Emissions: Nitrogen Oxides

Ozone (O3)• Properties: colorless, unpleasant odor,

major part of photochemical smog• Effects: lung irritant, damages plants,

rubber, fabric, eyes, 0.1 ppm can lower PSN by 50%,

• Sources: Created by sunlight acting on NOx and VOC , photocopiers, cars, industry, gas vapors, chemical solvents, incomplete fuel combustion products

• Class: photochemical oxidants

Ozone (O3)• 10,000 to 15,000 people in US admitted

to hospitals each year due to ozone-related illness

• Children more susceptible– Airways narrower– More time spent outdoors

Mobile Source Emissions: Hydrocarbons –

Precursors to Ozone

Carbon Monoxide (CO)• Properties: colorless, odorless, heavier than

air, 0.0036% of atmosphere

• Effects: binds tighter to Hb than O2, mental functions and visual acuity, even at low levels

• Sources: incomplete combustion of fossil fuels 60 - 95% from auto exhaust

• Class: carbon oxides (CO2, CO)

• EPA Standard: 9 ppm

• 5.5 billion tons enter atmosphere/year

Mobile Source Emissions - CO

Lead (Pb)• Properties: grayish metal• Effects: accumulates in tissue; affects

kidneys, liver and nervous system (children most susceptible); mental retardation; possible carcinogen; 20% of inner city kids have [high]

• Sources: particulates, smelters, batteries• Class: toxic or heavy metals• EPA Standard: 1.5 ug/m3

• 2 million tons enter atmosphere/year

Suspended Particulate Matter (PM10) •Properties: particles suspended in air (<10

um)

•Effects: lung damage, mutagenic, carcinogenic, teratogenic

•Sources: burning coal or diesel, volcanoes, factories, unpaved roads, plowing, lint, pollen, spores, burning fields

•Class: SPM: dust, soot, asbestos, lead, PCBs, dioxins, pesticides

•EPA Standard: 50 ug/m3 (annual mean)

Mobile Source Emissions: Fine Particulate Matter (PM2.5)

Sulfur Dioxide (SO2) • Properties: colorless gas with irritating odor• Effects: produces acid rain (H2SO4),

breathing difficulties, eutrophication due to sulfate formation, lichen and moss are indicators

• Sources: burning high sulfur coal or oil, smelting or metals, paper manufacture

• Class: sulfur oxides• EPA Standard: 0.3 ppm (annual mean)• Combines with water and NH4 to increase

soil fertility

VOCs (Volatile Organic Compounds)• Properties: organic compounds (hydrocarbons) that evaporate

easily, usually aromatic • Effects: eye and respiratory irritants; carcinogenic; liver, CNS, or

kidney damage; damages plants; lowered visibility due to brown haze; global warming

• Sources: vehicles (largest source), evaporation of solvents or fossil fuels, aerosols, paint thinners, dry cleaning

• Class: HAPs (Hazardous Air Pollutants) – Methane– Benzene– Chlorofluorocarbons (CFCs), etc.

• Concentrations indoors up to 1000x outdoors• 600 million tons of CFCs

Other Air Pollutants• Carbon dioxide• ChloroFluoroCarbons• Formaldehyde• Benzene• Asbestos• Manganese• Dioxins• Cadmium• Others not yet fully characterized

Factors that increase and/or decrease pollution

• Local climate (inversions, air pressure, temperature, humidity)

• Topography (hills and mountains)• Population density• Amount of industry• Fuels used by population and industry for heating,

manufacturing, transportation, power• Weather: rain, snow,wind• Buildings (slow wind speed)• Mass transit used• Economics

Pollutants

warmair

cool air

• surface heated by sun• warm air rises (incl. pollutants)• cools off, mixes with air of equal density & disperses

cool air

warm air (inversion layer)

• surface cools rapidly (night)• a layer of warm air overlays surface• polluted surface air rises but cannot disperse ⇒ remains trapped

Thermal Inversion

...when polluted air is stagnant (weather conditions, geographic location)

Los Angeles, CA

Smog Forms

Pollution • The term “Smog” (smoke and fog) was first

used in 1905 to describe sulfur dioxide emission

• In 1952, severe pollution took the lives of 5000 people in London

• “It isn’t pollution that’s harming the environment. It’s the impurities in our air and water that are doing it.” Former U.S. Vice President Dan Quaylewww.aqmd.gov/pubinfo/ 97annual.html

Photochemical Smog

Primary Pollutants

NO2 + Hydrocarbons

Auto Emissions

UV radiation

H2O + O2

Secondary Pollutants

HNO3 O3

nitric acid ozone

Photochemical Smog

Solarradiation

Ultraviolet radiation

NONitric oxide

P h o t o c h e m i c a l S m o g

H2OWater

NO2

Nitrogendioxide

Hydrocarbons

O2

Molecularoxygen

HNO3

Nitric acid

PANsPeroxyacyl

nitrates

Aldehydes(e.g., formaldehyde)

O3

Ozone

OAtomicoxygen

Photochemical Smog

Indoor Air Pollution

Why is indoor air quality important?

• 70 to 90% of time spent indoors, mostly at home

• Many significant pollution sources in the home (e.g. gas cookers, paints and glues)

• Personal exposure to many common pollutants is driven by indoor exposure

• Especially important for susceptible groups – e.g. the sick, old and very young

Exposure• Time spent in various environments in US

and less-developed countries

House of Commons Select Committee Enquiry on Indoor Air Pollution (1991)

• “[There is] evidence that 3 million people have asthma in the UK… and this is increasing by 5% per annum.”

• “Overall there appears to be a worryingly large number of health problems which could be connected with indoor pollution and which affect very large numbers of the population.”

• [The Committee recommends that the Government] “develop guidelines and codes of practice for indoor air quality in buildings which specifically identify exposure limits for an extended list of pollutants…”

Sources of Indoor Air Pollutants• Building materials

• Furniture

• Furnishings and fabrics

• Glues

• Cleaning products

• Other consumer products

• Combustion appliances (cookers and heaters)

• Open fires

• Tobacco smoking

• Cooking

• House dust mites, bacteria and moulds

• Outdoor air

Important Indoor Air pollutants• Nitrogen dioxide

• Carbon monoxide

• Formaldehyde

• Volatile Organic Compounds (VOCs)

• House dust mites (and other allergens, e.g. from pets)

• Environmental tobacco smoke

• Fine particles

• Chlorinated organic compounds (e.g. pesticides)

• Asbestos and man-made mineral fibres

• Radon

Health EffectsNitrogen dioxide• Respiratory irritant

• Elevated risk of respiratory illness in children, perhaps resulting from increased susceptibility to respiratory infection; inconsistent evidence for effects in adults

• Concentrations in kitchens can readily exceed WHO and EPA standards

Health Effects

Carbon monoxide• An asphyxiant and toxicant

• Hazard of acute intoxication, mostly from malfunctioning fuel-burning appliances and inadequate or blocked flues

• Possibility of chronic effects of long-term exposure to non- lethal concentrations, particularly amongst susceptible groups

Health Effects

Formaldehyde• Sensory and respiratory irritant and sensitizer

• Possible increased risk of asthma and chronic bronchitis in children at higher exposure levels

• Individual differences in sensory and other transient responses

• Caution over rising indoor concentrations

Health Effects

Volatile Organic Compounds (VOCs)• Occur in complex and variable mixtures

• Main health effects relate to comfort and well-being, but benzene (and other VOCs) are carcinogenic

• Concern about possible role of VOCs in the aetiology of multiple chemical sensitivity; also implicated in sick building syndrome

Health Effects

House dust mites• House dust mites produce Der p1 allergen, a potent

sensitizer

• Good evidence of increased risk of sensitization with increasing allergen exposure, but this does not necessarily lead to asthma

• Small reductions in exposure will not necessarily lead to reduced incidence and/or symptoms

• Indoor humidity is important

Health Effects

Fungi and bacteria• Dampness and mould-growth linked to self-

reported respiratory conditions, but little convincing evidence for association between measured airborne fungi and respiratory disease

• Insufficient data to relate exposure to (non-pathogenic) bacteria to health effects in the indoor environment

Health Effects

Environmental tobacco smoke (ETS)• Sudden infant death syndrome

• Lower respiratory tract illness • Middle ear disease • Asthma 12 million children exposed to secondhand

smoke in homes

Health EffectsFine particles• Consistent evidence that exposure to small

airborne particles (e.g. PM10) in ambient air can impact on human health; mechanisms uncertain

• Chronic Obstructive Pulmonary Disease and Cardiovascular Disease patients and asthmatics probably at extra risk

• Relative importance of indoor sources is unknown

Health Effects

Radon• Can cause lung cancer

• Estimated that 7,000 to 30,000 Americans die each year from radon-induced lung cancer

• Only smoking causes more lung cancer deaths

• Smokers more at risk than non-smokers

Radon Risk: Non-SmokerRadon Level

(pCI/L)If 1000 people who did not smoke were

exposed to this level over a lifetime.. About X would get lung cancer

This risk of cancer from radon exposure compares

to …What to do:

20 8 Being killed in a violent crime

Fix your home

10 4 Fix your home

8 3 10x risk of dying in a plane crash

Fix your home

4 2 Risk of drowning Fix your home

2 <1 Risk of dying in a home fire

Fix your home

1.3 <1 Average indoor radon level Fix your home

0.4 <1 Average indoor radon level Fix your home

If you are a former smoker, your risk may be higher

Radon Risk: SmokerRadon Level

(pCI/L)If 1000 people who smoke were

exposed to this level over a lifetime.. About X would get lung cancer

This risk of cancer from radon exposure compares

to …

What to do:Stop smoking and

…

20 135 100x risk of drowning Fix your home

10 71 100x risk of dying in a home fire

Fix your home

8 57 Fix your home

4 29 100x risk of dying in a plane crash

Fix your home

2 15 2x the risk of dying in a car crash

Fix your home

1.3 9 Average indoor radon level Fix your home

0.4 3 Average indoor radon level Fix your home

If you are a former smoker, your risk may be lower

Radon

• 55% of our exposure to radiation comes from radon

• colorless, tasteless, odorless gas• formed from the decay of uranium• found in nearly all soils• levels vary

(From: http://www.epa.gov/iaq/radon/zonemap.html)

Zone pCi/L 1 >4 2 2 - 4 3 <2

Radon: How it Enters Buildings

• Cracks in solid floors

• Construction joints

• Cracks in walls

• Gaps in suspended floors

• Gaps around service pipes

• Cavities inside walls

• The water supply

http://www.epa.gov/iaq/radon/pubs/citguide.html#howdoes

Radon: Reducing the Risks• Sealing cracks in floors and walls • Simple systems using pipes and fans

• More information: http://www.epa.gov/iaq/radon/pubs/consguid.html#reductiont

ech

Sick Building Syndrome (SBS)

vs

Building Related Illness (BRI)

Sick Building Syndrome

• A persistent set of symptoms in > 20% population

• Causes(s) not known or recognizable• Complaints/Symptoms relieved after exiting

building

Complaints/Symptoms

• Headaches

• Fatigue

• Reduced Mentation

• Irritability

• Eye, nose or throat irritation

• Dry Skin• Nasal Congestion• Difficulty Breathing• Nose Bleeds• Nausea

Building Related Illness• Clinically Recognized Disease• Exposure to indoor air pollutants• Recognizable Causes

Clinically Recognized Diseases

–Pontiac Fever – Legionella spp.–Legionnaire's Disease–Hypersensitivity Pneumonitis–Humidifier Fever–Asthma–Allergy–Respiratory Disease

• Chronic Obstructive Pulmonary Disease

Ventilation

Movement of Air Into / Out of Homes• Amount of air available to dilute pollutants

– important indicator of the likely contaminant concentration

• Indoor air can mix with outside air by three mechanisms– infiltration– natural ventilation– forced ventilation

Movement of Air Into / Out of Homes• Infiltration

– natural air exchange that occurs between a building and its environment when the doors and windows are closed

– leakage through holes or openings in the building envelope

– pressure induced• due to pressure differentials inside and outside of the

building

• especially important with cracks and other openings in wall

Movement of Air Into / Out of Homes

• Infiltration– Temperature induced (stack effect)

• driven by air movement through holes in floors, ceilings

• in winter, warm air in a building wants to rise, exits through cracks in ceiling and draws in

Movement of Air Into / Out of Homes• Natural ventilation

– air exchange that occurs when windows or doors are opened to increase air circulation

• Forced ventilation– mechanical air handling systems used to induce air

exchange using fans and blowers

• Trade-offs– cut infiltration to decrease heating and cooling costs vs.

indoor air quality problems

Movement of Air Into / Out of Homes• Infiltration rates

– Influenced by• how fast wind is blowing, pressure differentials• temperature differential between inside and

outside of house• location of leaks in building envelope

Air Pollution Prevention

TheClean

AirAct

Congress found:

• Most people now live in urban areas

• Growth results in air pollution

• Air pollution endangers living things

It decided:

• Prevention and control at the source was appropriate

• Such efforts are the responsibility of states and local authorities

• Federal funds and leadership are essential for the development of effective programs

Clean Air Act

• Originally signed 1963– States controlled standards

• 1970 – Uniform Standards by Federal Govt.– Criteria Pollutants

• Primary – Human health risk• Secondary – Protect materials, crops,

climate, visibility, personal comfort

Clean Air Act

• 1990 version – Acid rain, urban smog, toxic air pollutants, ozone

depletion, marketing pollution rights, VOC’s

• 1997 version– Reduced ambient ozone levels– Cost $15 billion/year -> save 15,000 lives – Reduce bronchitis cases by 60,000 per year– Reduce hospital respiratory admission 9000/year

Clean Air Act

President George W. Bush signed rules amending Clean Air Act that allowed power

plants and other industries to increase pollution significantly without adopting

control measures

Clean Air Act http://www.epa.gov/air/oaq_caa.html

• Title I - Air Pollution Prevention and Control– Part A - Air Quality and Emission Limitations

– Part B - Ozone Protection (replaced by Title VI)

– Part C - Prevention of Significant Deterioration of Air Quality

– Part D - Plan Requirements for Nonattainment Areas

• Title II - Emission Standards for Moving Sources– Part A - Motor Vehicle Emission and Fuel Standards

– Part B - Aircraft Emission Standards

– Part C - Clean Fuel Vehicles

• Title III - General

• Title IV - Acid Deposition Control

• Title V - Permits

• Title VI - Stratospheric Ozone Protection

Specific Air Pollution Treatment Technology

• Traditional– Move factory to remote location– Build taller smokestack so wind blows pollution

elsewhere

• New– Biofiltration : vapors pumped through soil where

microbes degrade– High-energy destruction: high-voltage electricity – Membrane separation: diffusion of organic

vapors through membrane– Oxidation: High temperature combustor

Absorption

Adsorption

Combustion

Cyclone

Filtration

Electrostatic Precipitator

Liquid Scrubber

Sulfur Dioxide Control

http://www.apt.lanl.gov/projects/cctc/factsheets/puair/adflugasdemo.html

Air Pollution Results

Comparison of 1970 and 1999 Emissions

Number of People Living in Counties with Air Quality Concentrations Above the Level of the National Ambient

Air Quality Standards (NAAQS) in 1999

Trends in Sulfur Dioxide Emissions Following Implementation of Phase I of the Acid Rain

Program: Total State-level Utility SO2 (1980, 1990, 1999)

FiftyYears

ofAir

Pollution

Figures are in millions of metric tons per year

MobileSources:The LastTen Years

-10%

-29%

-8%

-85%

-3%

-24%

VOCs CO NOx PM10 SOx Lead

Percent reductions shown are based on estimates of tons/year from mobile sources over the 1981 - 1990 time period

Who isAffected by

Air Pollution?

63

22

9

19

15

Ozone CO NO2 PM10 SO2 Lead

Millions of people living in counties with air quality that exceeds each NAAQS (1990 data)

Over 74 million people are subjected to high levels of at least one of these pollutants

Milestonesin the

Controlof

AutomotiveEmissions

1952 - Autos linked to air pollution

1963 - Original CAA, PCV valves

1968 - HC & CO exhaust controls

1970 - CAA amendments, EPA formed

1971 - Evaporative controls

1972 - First I/M Program

1973 - NOx exhaust controls

1975 - First catalytic converters

1981 - New cars meet statutory limits

1989 - Volatility limits on gasoline

1990 - New CAA Amendments

•1987 Montreal Protocol: CFC emissions should be reduced by 50% by the year 2000 (they had been increasing 3% per year.)

•1990 London amendments: production of CFCs, CCl4, and halons should cease entirely by 2000.

•1992 Copenhagen agreements: phase-out accelerated to 1996.

Goals of Kyoto Protocol

Reduction of greenhouse gases to below 1990 levels:

5.2% world wide reduction on average by 2008-2012

6% for Canada by 2008-2012

When sufficient countries ratify the Protocol (at least 55 countries comprising at least

55% of emissions), Protocol comes into effectUSA - 25% of emissions

Kyoto Emissions Agreement