You see it every time that smoke billows from your car's exhaust pipe, so there's no denying that vehicles are major contributors to air pollution. Air pollution refers to the presence of foreign substances in the air that don’t belong there, or
You see it every time that smoke billows from your car's exhaust pipe, so there's no denying that vehicles are major contributors to air pollution. Air pollution refers to the presence of foreign substances in the air that don’t belong there, or excessive amounts of certain impurities that wouldn't harm us otherwise. When cars burn gasoline, they emit pollutants. Gasolinefumes escape into the air even when we pump gasoline into our fuel tanks.
There are four major pollutants that come from cars:
- A car emits carbon monoxide when the carbon in fuel doesn't burn completely.
- A car's exhaust emits hydrocarbons, a toxic compound of hydrogen and carbon.
- When fuel burns, nitrogen and oxygen react with each other and form nitrogen oxides (NOx).
- Particulate matter -- small particles of foreign substances -- in the air contribute to atmospheric haze and can damage people’s lungs.
Pollutants from cars contribute to various types of air pollution. When hydrocarbons and NOx combine in sunlight, they produce ozone. High in the atmosphere, ozone protects us from the sun’s ultraviolet rays. When holes in the atmosphere's ozone layer allows ozone to come closer to Earth, it contributes to smog and causes respiratory problems.
Air pollutants emitted from cars are believed to cause cancer and contribute to such problems as asthma, heart disease, birth defects and eye irritation.
Emissions from cars increase the levels of carbon dioxide (CO2) and other greenhouse gases in the atmosphere. At normal levels, greenhouse gases keep some of the sun’s heat in the atmosphere and help warm the Earth. That said, many scientists believe that burning fossil fuels such as gasoline causes greenhouse gas levels to spike, leading to global warming.
Scientists use sophisticated instruments to measure concentrations of harmful substances in the air, but it’s tough to say exactly what percentage of air pollution comes from cars. This makes sense, because many other human activities contribute to air pollution as well. In fact, the production of electricity by coal-fired power plants and other sources can cause more pollution than most cars. If that wasn't enough, we pollute the air when we heat our homes and public buildings with fuels other than electricity -- just as we do when we drive our cars. Even people who don’t drive add to pollution when they buy goods and services that involve fuel when they're made or delivered.
Although the U.S. Environmental Protection Agency (EPA) declared cars "mobile sources" of pollution, they aren’t the only culprits. Big trucks, bulldozers and other, ships and boats, trains and even snowblowers pollute the air.
Acco