Air

What causes air pollution?

Chapter 12

Section 1

Air Pollution

• Harmful substances build up in the air to unhealthy levels

• Primary – put directly into the air by human activity

• Secondary – primary pollutant comes into contact with other primary pollutants or other substances such as water vapor and a chemical reaction takes place

Primary Pollutants in the U. S.

• Carbon monoxide – cars, trucks, buses, small engines

• Nitrogen oxide – burning fuels in vehicles, power plants, industrial boilers

• Sulfur dioxide – burning fossil fuels• Volatile organic compounds – burning fuels,

especially vehicles• Particulate matter – construction, agriculture,

forestry & fires, vehicles, industry

Motor Vehicle Emissions

• One-third of air pollution comes from gasoline burned in vehicles

• Clean Air Act of 1970 and 1990 allows EPA to regulate emissions

• ZEV – zero emission vehicles, no tailpipe, no emissions form gasoline, and no emission control systems that wear-out over time. Est. in 1990 in California, adopted by Maine, Massachusetts, New York and Vermont

Industrial Air Pollution

• Industry and power plants burn fossil fuels which release nitrogen oxide and sulfur dioxide

• Clean Air Act requires scrubbers to clean air from smoke stacks

• Smog – combination of auto exhaust and ozone, caused by pollutants from vehicles and industry

Smog

Temperature Inversions• Air above is warmer than the air below so

pollution is trapped in the lower layer