Ch-9 air pollution and city
Primary air pollutants:
- Air pollutants are composed of either visible particles – ash, smoke or dust OR invisible particles –
fumes, mists and odors
- Primary air pollutants are generated when fossil fuels are used – 3 primary fossil fuels – coal,
natural and petroleum – used for energy and transportation
- These fossil fuels are carbon based, release carbon monoxide and carbon dioxide when
combusted, coal also contains sulfur and nitrogen oxides
- Most common pollutants are called criteria pollutants b/c EPA uses them as basis for setting
permissible levels. One set of limits, called primary standard – to protect health, another set of
limits called, secondary standard – to prevent environmental and property damage
- Criteria pollutants are most regulated air pollutants – focused on limiting their usage and
discharge, not eliminate the cause
- Difficulty arises from variety of sources – generation of energy, use and combustion of fossil fuels
in transportation and agriculture, motor vehicle exhaust – due to increase in # of vehicles on road
- City that does not meet standard pollutant – called non-attainment area must create an action plan
– must include targets for reduction of pollutants, ways to encourage use of public transportation,
decrease use of single-occupancy vehicles, outreach and educate people,
- Ozone smog – most challenging pollution problem – most urban areas exceed air qualities
concentration for ozone and progress on ozone has been slowest
Photochemical smog:
- Smog occurs when VOC’s (volatile organic compounds) react with nitrogen and oxygen oxides in
presence of heat and sunlight – smog is not emitted, is created through series of chemical reactions
– produced by combinations of pollutants from many sources – smoke-stacks, cars, paint and
solvents
- Smog is found primarily in urban areas, worse in summer due to heat and sunlight at peak, highly
corrosive to rubber, metals and lung tissue
- Short-term exposure – eye irritation, wheezing, coughing, headaches, chest pain; long-term – scars
lungs, makes them less elastic and efficient, asthma, respiratory illness
- Geography location – cities located in basins and valleys – LA, Mexico, Denver – high altitudes,
frequent temperature warm air trapped under cold air
- Cities with high concentration of fossil-fuel burning power plants, melting smelters, cement and
fertilizer factories, high density of cars, trucks
- Air quality index – educate people about how to respond high levels of smog. When ozone is high,
smog alerts to warn people with asthma, chronic disease, stay indoors, healthy people shouldn’t
exercise outside
o Another category of pollutants that are hazard & toxic – can cause cancer or kill swiftly – 1984
Bhopal accidental leakage of pesticide – report of mouth cancer, kidney, liver damage
o In urban areas toxic air pollutants are serious concern because of conc
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