Air Pollution

                                                                                                        

Sources of Pollution

• Point Sources• Non-Point Sources• Primary Pollutants• Secondary

Pollutants• Natural Sources

– Larger than anthropogenic sources

Thermal Inversions

• Warm air on top of a layer of cool air near surface

• Prevents pollutants from rising & dispersing

Major Categories of Air Pollutants: Regulated by the

Clean Air Act

• Carbon Monoxide• Nitrogen Oxides• Sulfur Oxides• Ozone• Lead• Suspended Particulate Matter• Volatile Organic Compounds

Carbon Monoxide

• Source: – burning fossil fuels

• Replaces oxygen in blood stream– Bonds to

hemoglobin• Only dangerous in

high concentrations

Nitrogen Oxides: Photochemical Smog

• Source: Automobiles (burning gasoline)

• NO2 + UV O3 + Nitrates

• Yellow-brown color, sweet smell

Sulfur Oxides: Industrial Smog

• Source: Coal-fired industry, electric

• SO2 + UV O3 + Sulfates

• Gray-air smog, colored by soot

Sulfur & Nitrogen Oxides:

Acid Rain• Source: Coal-fired industry, electric

• Normal Rain pH 5.6– CO2 + H2O H2CO3 (normal)

– NO2 + H2O HNO3 (contributes)

– SO2 + H2O H2SO4 (strong

acid)

• Secondary pollutant• Limestone acts as a

buffer: neutralize acid

Effects of Acid Deposition

• Human respiratory illness• Leach toxic metals from

pipes to water• Damage building materials• Lakes – acid shock

– Release Al3+ into water – asphyxiate fish

– Dissolve nutrients - reduce algal growth

• Plants and soils– Weakens trees, competition

with mosses– Acids leach minerals from soil

Ground-level Ozone

• Source: burning fossil fuels• Secondary Pollutant!

– Formed from rxns with UV

• Health Effects– Chest pain, coughing, throat irritation,

congestion– Worsen respiratory disease (bronchitis,

asthma, etc.)

• Environmental Damage– Damage leaves, reduce crop yields

Lead• Source: industry, waste incinerators

– Regulations removed lead from gasoline

• Toxicant, accumulates in bones– Neurological, kidney, immune and

reproductive systems

Particulate Matter

• Source: dust, fires, volcanoes, fossil fuels

• Regulated PM10 and PM2.5

– Smaller than 10 um (thickness of one hair strand)

• Health effects– Lung irritation, reduced visibility, altered

nutrient balance, damage to crops

Reducing Pollution• Carbon Monoxide

– CO detectors in homes• Nitrogen Oxides

– Catalytic converters and regulations on vehicles

• Sulfur Oxides– Scrubbers on smokestacks

• Ozone• Lead

– Unleaded gasoline, removed from paints• Particulates

– Spray mines and construction with water

Clean Air Act• 1970, ammended 1977 & 1990

– Comprehensive regulations on 6 common air pollutants: CO, NOx, SOx, O3, PM10, lead

– Addressed acid rain, toxic emissions, ozone depletion, automobile exhausts

– Created NAAQS (National Ambient Air Quality Standards)

– Gave enforcement authority: mainly controlled and enforced by state governments

                                                                                                                                                                                                   

Air Quality Index