Air Pollution
Primary Pollutants: Come from:
Natural sources (volcanoes) Mobile sources (cars) Stationary sources (smoke
stacks) Examples:
Particle matter or soot (PM10) Nitric oxide (NO) Nitrogen dioxide (NO2) Sulfur dioxide (SO2) Carbon dioxide (CO2) Carbon monoxide (CO)
Secondary Pollutants: Result from chemical
reactions of primary pollutants in the atmosphere
Examples: Sulfur trioxide (SO3) Sulfuric acid (H2SO4) Ozone (O3)
Major Air Pollutants
Criteria air pollutants Set of pollutants that cause smog, acid rain, and
other health hazards Emitted from industry, mining, transportation,
power generation, and agriculture Include: ozone, particulate matter, carbon
monoxide, sulfur dioxide, nitrogen oxides, and lead
Major Air Pollutants
Nitrogen Dioxide (NO2) Forms when fuels burn at
high temperatures, from forest fires, volcanoes, and bacteria in soil
Forms nitric acid in the air acid deposition
When inhaled irritates the lungs
Supresses plant growth May be a carcinogen
Ozone (O3) Formed by the reaction of
sunlight and NOx and VOCs
Causes: Lung irritation and
damage Bronchial constriction Coughing Wheezing Eye irritation
In high atmosphere forms ozone layer = good
Major Air Pollutants
Peroxyacyl Nitrates (PANs)Hydrocarbons + O2 +NO2 + light CH3COOONO2 (PAN)Stable in the atmosphere transport unstable compounds far away from urban centersCause eye irritation In high concentrations damage vegetation
Sulfur Dioxide (SO2) Produced by burning high-
sulfur oil or coal, smelting of metals, and paper manufacturing
Combines with water vapor to produce acid rain
Acid rain causes: Reduction in plant
productivity Breathing difficulties Destroys buildings Acidifies water supply
Major Air Pollutants Suspended Particulate
Matter (PM10) Particles with a diameter of
1/7 of a human hair or less Include smoke, dust, diesel
soot, lead, and asbestos Cause lung irriation and
damage Are mutagens, teratogens
(interfers with development), and carcinogens
Reducing PM10 would produce health benefits 10 times grater than reducing all other air pollutants combined
Volatile Organic Compounds (VOCs) Include organic compounds
that have a high vapor pressure
Found in paints, aerosol sprays, dry-cleaning fluids, and industrial solvents
Cause respiratory irritation and damage
Most are carcinogens Cause liver, kidney, and
central nervous system damage
May be greater concentrations indoors than outdoors
Measurement Units
ppm (Parts per million) 1ppm means every 999,999 particles of air there
is 1 particle of pollutant
Others: ppb or nano: parts per billion ppt or pico: parts per trillion
Smog
Industrial: tends to be sulfur based Called “grey-air” smog
Photochemical: nitrogen based Catalyzed by UV radiation Called “brown-air” smog
Formation of industrial smogStep Chemical Reaction
1. Carbon in coal or oil is burned in oxygen gas to produce carbon dioxide and carbon monoxide
C + O CO2
C + O CO
2. Unburned carbon ends up as soot or particulate matter
C
3. Sulfur in oil and coal reacts with oxygen gas to produce sulfur dioxide
S + O SO2
4. Sulfur dioxide reacts with oxygen gas to produce sulfur trioxide
SO2 + O2 SO3
5. Sulfur trioxide reacts with water vapor in the air to form sulfuric acid
SO3 + H2O H2 SO4
6. Sulfuric acid reacts with atmospheric ammonia to form brown, solid ammonium sulfate
H2 SO4 + NH3 (NH2)2SO4
Formation of photochemical smog
Occurs during specific times of the day
Net Result:
NO + VOCs + O2 + uv O3 + PANs
Formation of photochemical smog
Time of day
Event Chemical Reactions
6 A.M. – 9 A.M.
People drive to work, concentrations of nitrogen oxides and VOCs increase
N2 + O2 2NO
NO + VOCs NO2
NO2 + uv NO + O
9 A.M. – 11 A.M.
As traffic begins to decrease nitrogen oxides and VOCs react to form nitrogen dioxide
2NO + O 2NO2
Formation of photochemical smog cont.
Time of day Event Chemical Reactions
11A.M. – 4 P.M.
As sunlight becomes more intentse, nitrogen dioxide is broken down and the concentration of ozone increaes
NO2 + uv NO + O
O2 + O O3
Nitrogen dioxide reacts with water vapor to produce nitric acid and nitric oxide
3 NO2 + H2O 2HNO3 + NO
Nitrogen dioxide can also react with VOCs released by vehicles , refineries, gas stations, and so on to produces toxic PANs
NO2 + VOCs PANs
4 P.M. – Sunset
Ozone production is halted
Case Study – Great Smog of ‘52
A period of cold weather combined with windless conditions to collect airborne pollutants (most form coal) to produce a thick layer of grey smog over London December 5 – 9 1952
Dispersed quickly after a change in weather 100,000 people became ill 12,000 died
Catalytic Converters
Converts toxic chemicals in engine exhaust to less noxious substances
Inside a catalyst stimulates a chemical reaction in which noxious by-products of combustion are converted to less toxic substances
Catalytic Converters
3 way converter: Reduction of nitrogen dioxides to nitrogen and oxygen Oxidation of carbon monoxide to carbon dioxide Oxidation of unburned hydrocarbons to carbon dioxide and
water.
Catalytic converters
Pros Remove hydrocarbons
and other harmful emissions
Cons Do not reduce carbon
dioxide emissions Release nitrous oxide
which contributes to climate change
Types of Acid Deposition
Wet: Acid rain Acid fog Acid snow Water flows over the
ground and affects plants and animals
Dry Acid gases Acid particles Particles fall out of
atmosphere and onto buildings, cars, trees, etc.
Rain can wash particles off features in the environment contributing to acid rain
Acid depositions
Due to: Sulfur dioxide Nitrogen oxides
Environmental effects: Acidify streams Damage forests soils through nitrogen saturation Acid shock (rapid melting of snow pack with acid
particles) Leaches essential plant nutrients from the soil
Heat Islands Occur in metropolitan areas Urban air is 10°F (6°C) warmer than surrounding
environment
Heat Islands Causes:
Buildings reduce radiation of heat to the atmosphere
Thermal properties of surface material (asphalt, bricks, concrete) store heat longer
Lack of vegetation and standing water increase temperatures
Human activities (automobiles, industry, etc.)
Effects: Combined with high
levels of pollution leads to a localized green house effect
Excessive temperatures can lead to deaths
Meteorological effects: Alter local wind patterns Alter the development
of clouds and fog Alter number of lighting
strikes Change precipitation
patterns
Combating urban heat islands
Increasing amount of landscaping in parks and on top of buildings
Increasing the amount of light or reflective material
Temperature Inversions
Occur when air temperature increases with height above the ground Usually occur at night when the surface cools,
cooling the air above it
Can lead to smog being trapped near the ground human health problems (asthma, emphysema, and increase in lung cancer)
Case Study- Donora, PA 1948
Smog from the local zinc and steel smelting plants settled in the valley where Donora was located
20 people asphyxiated and 7,000 went to the hospital (total population of the town was 14,000)
Four days later, wind cleared the toxins from the town
Led to first meaningful federal and state laws to control air pollution
Indoor Air Pollution
Indoor air pollution is 25% to 60% greater than outdoor pollution
Sick Building Syndrome (SBS) describes a combination of ailments associated with a place of work or residence
Common Pollutants: Mold Bacteria Carbon monoxide Radon Allergens Asbestos Tobacco smoke Formaldehyde VOCs
Air Pollution Remediation and Reduction Strategies
1. Emphasizing tax incentives for pollution control rather than fines and penalties
2. Setting legislative standards for energy efficiency
3. Increasing funding for research into renewable energy resources
4. Incorporating incentives for reducing air pollution into trade policies
5. Distributing solar cook stoves to developing countries to replace coal and firewood
Air Pollution Remediation and Reduction Strategies
6. Phasing out two-cycle gasoline engines7. For issues involving SBS
a. Modify building codes to control materials used in construction
b. Replace and repair areas that have received water damage to control for mold
c. Use paints, adhesives, solvents, cleaning products, and pesticides in well-ventilated areas and during non-occupancy
d. Increase the number of complete air exchanges in buildings
e. Ensure proper maintenance of HVAC systems8. Providing incentives to use mass transit
Combating Acid Rain
Design more efficient engines to reduce emissions
Reduce emissions in coal-burning power plants
Increase penalties on stationary sources Provide incentives to consumers to purchase
Energy Star products Increase CAFE standards
EPA’s Acid Rain Program Designed to achieve
significant environmental reduction and public health benefits through reductions in emission of sulfur and nitrogen compounds at a low cost to society
Encourages energy efficiency and pollution prevention
Strategies: Allowance trading system Opt-in program, allows non-
affected industrial and small utility units to participate in trading
Setting new NOx emission standards
Permit process that affords flexibility in selecting most cost-effective approach
Continuous Emissions Monitoring (CEM) provide accounting of excess emissions
Clean Air Act (1963) Designed to control
pollution on a national level Act has been amended in
1967, 1977, 1990 Requires EPA to design and
enforce regulations to protect the public from airborne contaminants
Required comprehensive federal and state regulations for both stationary and mobile sources of pollution
Expanded federal enforcement authority
Addressed acid rain, ozone depletion, and toxic air pollution
Established new gasoline reformulation requirements
1st major environmental law to include provisions for citizen law suits
Clean Air Act (1963) is responsible for:
Estimates responsible for: Saving 15,000 lives per
year Reducing bronchitis by
60,000 cases each year Reducing respiratory
related illnesses by 9,000 cases each year
Pollutant Changes
Pollutant % Change
Pb (lead) -98%
VOC -42%
SO2 -37%
CO -31%
NOx +17%
PM10 +266%
Relevant laws
Air Pollution Control Act (1955) 1st legislation regarding air pollution Identified air pollution as a national problem Announced research and additional steps were
necessary Basically meant to make public aware of problem
National Environmental Policy Act (1970) Created EPA Mandated the creation of Environmental Impact
Statements
Relevant laws
Montreal Protocol (1989) Agreement among nations to phase out
chemicals that damage the ozone layer
Pollution Prevention Act (1990) Requires industry to reduce pollution at its source Reduction can be in terms of volume and/or
toxicity
Kyoto Protocol (1997 and 2001) An agreement among 150 nations requiring
greenhouse gas reductions Would have required a 7% decrease in greenhouse
gas emissions compare to 1990 levels over a 5 year period US felt protocol held developed and developing countries
to different standards Concerned the costs were too high and time frame too
short; climate change deniers 2012: Canada, Japan, and Russia joined the US
saying they would not sign an agreement unless unbalanced requirements for developed and developing countries were changed
Noise Pollution
Unwanted human-created sound that disrupts the environment Transportation noise (dominant) Office equipment Factory machinery Appliances Power tools Audio entertainment systems
Noise Pollution Effects
Short Term Damage to inner ear
results in hearing loss Cardiovascular problems Gastric-intestinal
problems Decrease alertness and
ability to memorize Nervousness, pupil
dilation Decrease in the visual
field
Long term Insomnia Nervousness Bulimia chronically high blood
pressure Anxiety Depression Sexual dysfunction
Noise Pollution Control Measures Road noise:
Use of noise barriers, limitations on vehicle speed
newer roadway surface technologies
traffic control limiting times for heavy duty
vehicles Air line Noise:
Developing quieter jet engines
controlling take off and landing times
Industrial Noise: New technologies Instillations of noise barriers
in the work place Residential Noise:
Regulate noise from power tools, garden equipement, loud radios
Relevant Law
Noise Pollution Control Act (1972): Establishes a national policy to promote an
environment free from noise that jeopardizes health
Establishes a means for the coordination of federal research activities in noise control
Authorizes establishment of federal noise standards and products
Provides information to the public respecting noise emission and noise reduction characteristics of such protocol