Air Pollution
Chapter 18-19
There is no place on Earth that isn’t
affected by air pollution…
 Air pollution: presence of chemicals in the atmosphere in
concentrations high enough to harm organisms, ecosystems,
human-made materials or to alter climate
 Ranges from annoying to lethal
 Refers to pollution in the troposphere
 Natural sources
 Dust, wildfires, volcanic eruptions
 Human sources
 Industrialized and urban areas
 fossil fuel burning
 Primary Pollutants: chemicals or substances emitted directly into the air
from natural sources and human activities
 Carbon monoxide, carbon dioxide, sulfur dioxide and nitric oxides;
particulate matter; VOCs (natural sources—terpenes, plant fragrance)
 Secondary Pollutants: primary pollutants react with one another and
natural components to form harmful chemicals, often in the presence of
sunlight and water
 Ozone, acid deposition (sulfates and nitrates)
 To determine and monitor Air Quality, the EPA actively monitors…
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carbon monoxide
ozone
lead
nitrogen dioxide
particulate matter (also known as particle pollution)
sulfur dioxide
Major Air Pollutants
 Carbon Oxides
 Carbon Dioxide: from fossil fuel burning (major pollutant);
is a greenhouse gas that impacts climate; required for
photosynthesis; colorless and odorless
 Carbon Monoxide: from combustion of carbon (exhaust,
forest burning, fossil fuels, tobacco smoke); Limits oxygen
binding in hemoglobin which can result in heart attack, asthma,
emphysema, nausea and death; colorless and odorless—
dangerous indoor air pollutant
 Nitrogen Oxides (NOx) and Nitric Acid
 Nitric Oxide (NO): combustion in cars, coal burning, lightning,
part of soil and water (nitrogen cycle); colorless and odorless
 Nitrogen Dioxide (NO2): nitrogen monoxide reacts with oxygen
(NO2); reacts with water to form nitric acid and nitrate salts (acid
deposition); forms photochemical smog (with sunlight); helps in the
formation of tropospheric ozone; stinky, reddish-brown gas
 Nitrous Oxide (N2O): greenhouse gas from fertilizers and animal
wastes, also fossil fuel burning
** all are irritants to eyes, nose and throat, aggravate asthma and
bronchitis; suppress plant growth and harm aquatic life
 Sulfur Dioxide and Sulfuric Acid
 Sulfur Dioxide (SO2): 1/3 comes from natural sources (sulfur
cycle), the rest is anthropogenic (coal burning, oil refining,
smelting); corrosive gas
 Sulfuric Acid: forms when SO2 reacts with water in the
atmosphere, then falls as acid deposition (acid rain).
**Aggravate breathing problems (respiratory irritant), decrease
plant growth, corrosive
 Particulates
 Suspended particulate matter (solid particles and liquid droplets); particles
smaller than 10 micrometers are regulated by the EPA as air pollution (not
filtered by nose/throat)
 Outdoor: dust, wildfires, sea salt, coal/oil burning, cars (especially diesel),
construction; road dust, rock crushing; volcanic activity
 Indoor: cigarettes, burning inside (developing countries)
**Aggravate eyes, nose, and throat, damage lungs,
asthma/bronchitis, genetic mutations, and cancer
(premature death)
**Reduces the amount of incoming solar radiation
(weather)
 Ozone (O3)
 Secondary pollutant that contributes to photochemical smog
 Tropospheric ozone bad. Stratospheric ozone good.
 Ozone thinning is the stratosphere…which increases the amount of UV
radiation that reaches us
 Damages living tissue
 Results from release of CFCs and other Freons…from coolants and
aerosols
 Montreal Protocol—Limit these chemicals in manufactured products
**Coughing and breathing problems (asthma and emphysema), lung/heart
disease, irritant; damaging to rubber and plastic
 Volatile Organic Compounds (VOCs)
 Organic compounds (hydrocarbons) that exist as gases in the
atmosphere
 Give off strong aroma (paint, perfume, gasoline, flatulence)
 Help in formation of smog, not all hazardous…but some have the
potential to be harmful
 Ex. Methane—greenhouse gas from landfills, cows, decomposition,
oil and gas burning/refining
 Others include benzene, industrial solvents, gas and plastics
 Mercury: found in coal and oil, released from fossil fuel
burning, can settle out into water. Seeing bioaccumulation into
food chains.
 Toxin for central nervous system
 Lead: occurs naturally in rocks and soils, also present in fuels and
paints.
 Toxic to central nervous system (children), affects learning,
concentration, and intelligence
Factors Affecting Air Pollution
 Increase air pollution
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Buildings break up wind
Hills/mountains decrease air flow
High temperature increases reactions
Emissions of VOCs increase smog formation
Temperature inversions (warm air over cool)
 Decrease air pollution
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Heavy particles settle out of air
Rain/snow cleanse air
Salty sea spray washes air
Winds mix air
Pollutants removed by reactions
Acid Deposition
 Air pollutants mix with water in air to form acidic precipitation (acid
rain)
 Nitrogen and sulfur oxides—form nitric and sulfuric acid (pH ~5)
 Has been occurring since the Industrial Revolution
 Usually a regional problem…downwind of coal burning facilities
 Pollutants are moved by winds
 Damages statues, buildings; causes respiratory diseases, leach toxic
metals into the environment from rocks; harmful to aquatic ecosystems,
hurts agriculture, and weakens forests and plants
 Reduced by limiting emissions of pollutants (alternative energy sources)
Smog
 Industrial
 Unhealthy mix of sulfur dioxide and sulfuric acid and solid particles
 Comes from coal burning in large quantities
 Rarely a problem in developed countries…big problem in
developing (China)
 Sulfur dioxide and sulfates mostly; “grey smog”
 Photochemical
 Mixture of primary and secondary pollutants formed under the
influence of UV radiation
 “brown smog”—made up mostly of ozone
Indoor vs. Outdoor Air Pollution
 Indoor Air Pollution from burning wood, charcoal in open fires or
poorly designed stoves; cigarette smoke
 Carbon monoxide and particulates
 Impacts high poverty/poor countries
 Sources include:
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Tobacco smoke
formaldehyde
Radon gas
Fine particulates
Pesticide residues
Lead
Organic solvents
Living organisms (mites, roaches)
Mold and fungal spores
Radon Gas
 Colorless, odorless radioactive gas that is produced by the
radioactive decay of uranium-238 (from underground rock)
 Only problematic in certain areas of the country
 Can seep through cracks in the foundation and build up to
harmful levels in air, or seep into groundwater
 Damages lung tissue and lead to cancer (second leading cause
of lung cancer)
 Radon-222 decays to Polonium-210 (harmful/carcinogen)
Dealing with Air Pollution
 Clean Air Act: set aside air pollution regulations
 EPA monitors pollutants and sets standards for emissions
 EPA's mission is to protect human health and the environment. To achieve this mission, EPA
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implements a variety of programs under the Clean Air Act that focus on:
reducing outdoor, or ambient, concentrations of air pollutants that cause smog, haze, acid rain,
and other problems;
reducing emissions of toxic air pollutants that are known to, or are suspected of, causing cancer
or other serious health effects; and
phasing out production and use of chemicals that destroy stratospheric ozone.
These pollutants come from stationary sources (like chemical plants, gas stations, and
powerplants) and mobile sources (like cars, trucks, and planes).
 Buy and sell pollution allotments
 Prevention in best solution!
 Improve fuel efficiency standards
 Alternative energy sources
 Educate public about pollution
Air Quality Index
 National Ambient Air Quality
Standards
 EPA sets standards for
pollutants harmful to humans
or the environment (clean air
act)
 Primary standards protect
public health
 Secondary standards protect
public welfare
 Carbon Monoxide, Lead,
Particulates, Ozone, Nitrogen
Dioxide and Sulfur Dioxide