Air Pollution Notes
Air pollutants mostly come from natural sources and from burning of fossil fuels in motor vehicles
(CARPOOL) and electric power and industrial plants
Primary pollutants=harmful substances emitted directly into the air
Secondary pollutants= primary pollutants that have reacted with something else in
the air to form yet another harmful substance
Over past 30 years air quality improving in developed countries
But WHO says that 1/6 on earth live in polluted urban area. Found in Densely populated
developing countries.
Indoor air pollution is from poor when they have to burn wood, charcoal, coal and dung in
open fires in house to eat or keep warm.
Criteria air pollutants
Carbon Oxides
CO, CO2
Carbon monoxide is colorless, odorless and highly toxic. Forms during the incomplete
combustion of carbon containing materials.
Sources include-car exhaust, tobacco smoke, burning of forests, and cooking with open
fires.
Result-reacts with hemoglobin in blood reducing content of oxygen absorbed
Carbon Dioxide is colorless, odorless. 93% of CO@ in the trop is the result of natural carbon
cycle. The remaining comes from human activities, burning fossil fuels, clearing of forests.
Not regulated under US Clean Air Act
Nitrogen Oxides and nitric acid
Power plants and transportation
NO-nitrogen oxide is colorless and forms when nitrogen and oxygen gas react at high combustion
temp like in automobiles. N2+O2=2NO
NO reacts with O2 to form Nitrogen Dioxide=NO2 (reddish brown gas)
When NO2 reacts with water it makes nitric acid (HNO3) This is acid rain component (secondary
pollutant)
NO and NO2 both play a role in photochemical smog (mix of chemicals formed under the
influence of sunlight in car centered cities.
Nitrous Oxide (N2O)is a green house gas and comes from animal waste, fertilizers and burning of
fossil fuels
Sulfur Dioxide and sulfuric acid
SO2 is colorless with irritating odor. 1/3 comes from natural resources as part of sulfur cycle.
2/3 comes from human sources, mostly combustion in sulfur containing coal and electric power
and industrial plants. (S+O2=SO2
Add water and you got H2SO4 or sulfuric acid (secondary pollutant)
Particulates
Suspended particulate matter (SPM) this can be liquid or solid. Mostly natural like dust, wild fires
Humans add by plowing fields, road construction, unpaved roads, tobacco smoke, coal
burning, and motor vehicles
VOC or Volatile organic compounds
Organic compounds that exist as gases in the air. Mosly hydrocarbons like methane, terpene,
isoprene which are natural from plants. However the rest come from solvents,
transportation,landfills, natural gas wells, cows, rice paddies.
Radon-222
Found in soil and rock long term exposure hurts lungs
KNOW THE CHART and pg 397 table 18.1
Clean Air Act of 1970
The enactment of the Clean Air Act of 1970 (1970 CAA) resulted in a major shift in the federal
government's role in air pollution control. This legislation authorized the development of
comprehensive federal and state regulations to limit emissions from both stationary (industrial)
sources and mobile sources. Four major regulatory programs affecting stationary sources were
initiated: the National Ambient Air Quality Standards [NAAQS (pronounced "knacks")], State
Implementation Plans (SIPs), New Source Performance Standards (NSPS), and National Emission
Standards for Hazardous Air Pollutants (NESHAPs). Furthermore, the enforcement authority was
substantially expanded. The adoption of this very important legislation occurred at approximately
the same time as the National Environmental Policy Act that established the U.S. Environmental
Protection Agency (EPA). The EPA was created on May 2, 1971 in order to implement the various
requirements included in the Clean Air Act of 1970.
Clean Air Act Amendments of 1977
Major amendments were added to the Clean Air Act in 1977 (1977 CAAA). The 1977
Amendments primarily concerned provisions for the Prevention of Significant Deterioration (PSD)
of air quality in areas attaining the NAAQS. The 1977 CAAA also contained requirements
pertaining to sources in non-attainment areas for NAAQS. A non-attainment area is a geographic
area that does not meet one or more of the federal air quality standards. Both of these 1977
CAAA established major permit review requirements to ensure attainment and maintenance of
the NAAQS.
Clean Air Act Amendments of 1990
Another set of major amendments to the Clean Air Act occurred in 1990 (1990 CAAA). The 1990
CAAA substantially increased the authority and responsibility of the federal government. New
regulatory programs were authorized for control of acid deposition (acid rain) and for the
issuance of stationary source operating permits. The NESHAPs were incorporated into a greatly
expanded program for controlling toxic air pollutants. The provisions for attainment and
maintenance of NAAQS were substantially modified and expanded. Other revisions included
provisions regarding stratospheric ozone protection, increased enforcement authority, and
expanded research programs.