Section #1: What Causes Air Pollution

Air Pollution when harmful substances build up in the air to unhealthy levels these harmful substances can be in the form of a solid, liquid, or gas most pollution is from human activities, but some comes from natural sources

Natural Sources of Air Pollution volcanoes – spew clouds of particles (ash) & gases (sulfur dioxide) dust (think about the dust kicked up from plowing a field) pollen & spores (growing season) salt from sea spray

Primary Pollutants pollutant that is put directly into the air by a human activity Example = soot from smoke (burning wood, industries, vehicles, etc.) main sources of primary pollutants = electricity, industry, & transportation

Sources of Primary Pollution in the U.S. per day

Other Primary Air Pollutants carbon monoxide nitrogen oxide sulfur dioxide chemicals called VOCs (volatile organic compounds) particulate matter (PM)

Sources of Air Pollutants vehicle exhaust emissions coal-burning power plants refineries metal smelters burning fuels mining operations incinerators wood-burning fireplaces fields & roads

VOCs from a Refinery

Secondary Pollutants when a primary pollutant comes in contact with other primary pollutants or with naturally occurring substances (like H2O vapor) and a chemical reaction takes place

Secondary Pollutants an example of a secondary pollutant is ground level ozone that forms when car & truck emissions react with the UV rays of the sun & then mix with O2 in the atmosphere

History of Air Pollution not a new phenomenon – occurs whenever something is burned there are records from 2000 years ago from a Roman philosopher complaining about the foul air in Rome in 1273, England’s King Edward I ordered the hanging of a citizen for disobeying the “clean air act” when he illegally burned a very dirty kind of coal called sea-coal

Motor Vehicle Emissions almost 1/3 of our air pollution comes from gasoline burned by vehicles the EPA started regulating emissions in 1980 required the gradual elimination of lead from gasoline & the addition of catalytic converters to tailpipes to clean exhaust gases of pollutants

Catalytic Converter

A Car’s Contribution of Air Pollution car seats can be covered in a plastic that contains a VOC called vinyl chloride steel smelters send 1000s of metric tons of SO2 into the atmosphere to produce the body & frame VOCs escape into the atmosphere whenever you fill the tank with gasoline

A Car’s Contribution of Air Pollution exhaust is a major source of nitrogen oxides, carbon monoxide, & hydrocarbons in some developing countries, exhaust can also contain poisonous substances each car releases 4.5 metric tons of CO2 each year

California - Zero Emission Program established in 1990 vehicles that have no tailpipe emissions, no emissions from gasoline, & no emissions from control systems by 2016, 16% of all vehicles (including SUVs, trucks, etc.) must be zero-emission vehicles

Zero-Emission Vehicles include electric cars & vehicles with advanced battery power vehicles powered by hydrogen fuel also includes partial zero-emission vehicles like hybrid-electric cars & cars with methanol fuel cells programs have been adopted by Maine, Massachusetts, New York, & Vermont

Industrial Air Pollution industries & power plants burn fossil fuels to get the energy they need this releases huge quantities of SO2 & NO into the air they also produce VOCs that form toxic fumes

Industries Producing VOCs oil refineries chemical manufacturing plants furniture refinishers automobile repair shops dry cleaners

VOC Emissions from Dry Cleaning

Regulating Industrial Pollution Clean Air Act requires many industries to use scrubbers or other pollution-control devices scrubbers remove some of the more harmful substances electrostatic precipitators are machines used in cement factories & coal-burning power plants to remove dust particles from smokestacks

The scrubber machine moves gases through a spray of water that dissolves many pollutants like ammonia

Electrostatic Precipitators gas containing dust particles is blown through a chamber containing an electrical current an electrical charge is transferred to the dust particles, causing them to stick to each other & the sides of the chamber

Smog when air pollution hangs over urban areas & reduces visibility results from chemical reactions that involve sunlight, air, automobile exhaust, & ozone affected cities include, LA, Denver, & Phoenix

How Smog Forms over Major Cities

Temperature Inversions air circulation usually keeps air pollution from reaching dangerous levels in the atmosphere as the suns warms the earth and the warm air rises up, it carries pollutants away from the ground sometimes though, pollution is trapped close to the surface with a temperature inversion

Temperature Inversions during an inversion, the temperatures of the air above are warmer than the air below this keeps the cooler air at the surface from moving upwards, thus trapping pollutants with the cooler air below chances increase when a city is in a valley & surrounded by mountains

Major Sources of Groundwater Pollution