12.1 what causes air pollution

ZEV programs have also been adopted by

Maine, Massachusetts, New York, and Vermont.

A scrubber is

a machine that moves gases through a spray of water that dissolves many pollutants.

secondary pollutant is

a pollutant that forms in the atmosphere by chemical reactions with primary air pollutants, natural components in the air, or both.

primary pollutant is

a pollutant that is put directly into the atmosphere by human or natural activity.

SOURCES OF PRIMARY AIR POLLUTANTS

Household products, power plants, and motor vehicles are sources of primary pollutants such as carbon monoxide, nitrogen oxide, sulfur dioxide, and chemicals called volatile organic compounds (VOCs).

pollutants enter the air

Whenever something burns

The circulation of air in the atmosphere usually keeps

air pollution from reaching dangerous levels.

In 1273, King Edward I ordered that

burning a particularly dirty kind of coal called sea-coal was illegal.

VOCs are

chemical compounds that form toxic fumes.

Smog results from

chemical reactions that involve sunlight, air, automobile exhaust, and ozone.

When people use some of the products that contain VOCs

even more VOCS are added to the air.

Many industries and power plants that generate our electricity must burn

fuel, usually fossil fuel, to get the energy they need.

The EPA required

he gradual elimination of lead in gasoline, decreasing lead pollution by more than 90 percent in the United States.

Most air pollution is the result of

human activities but some pollutants are natural, including dust, pollen, spores, and sulfur dioxide from volcanic eruptions.

The Clean Air Act requires

many industries to use scrubbers or other pollution-control devices.

The Clean Air Act, passed in 1970 and strengthened in 1990, gives the Environmental Protection Agency (EPA) the authority to

regulate vehicle emissions in the United States.

Substances that pollute the air can be in the form of

solids, liquids, or gases.

Scrubbers remove

some of the more harmful substances that would otherwise pollute the air. Ammonia is an example

Burning fossil fuels releases huge quantities of

sulfur dioxide and nitrogen oxide into the air.

Power plants that produce electricity emit

t least two-thirds of all sulfur dioxide and more than one-third of all nitrogen oxides that pollute the air.

Zero-emission vehicles are vehicles that have no

tailpipe emissions, no emissions from gasoline, and no emission-control systems that deteriorate over time.

Sometimes, however, pollution is trapped near Earth's surface by a

temperature inversion.

A temperature inversion is

the atmospheric condition in which warm air traps cooler air near Earth's surface.

Air pollution is

the contamination of the atmosphere by wastes from sources such as industrial burning and automobile exhausts.

Ground level ozone forms when

the emission from cars react with the UV rays of the sun and then mix with the oxygen in the atmosphere.

In 1990, the California Air Resources Board established

the zero-emission vehicle (ZEV) program.

Dry cleaning, oil refineries, chemical manufacturing plants, furniture refinishers, and automobile repair shops all contribute

to the VOCs in the air.

Smog is

urban air pollution composed of a mixture of smoke and fog produced from industrial pollutants and burning fuels.

Pollutants released by

vehicles and industries are the main causes of smog.

Most air pollution in urban areas comes from

vehicles and industry.