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Air Pollution Facts

What contributes to air pollution?

The air we breathe in many cities is being polluted by driving cars and trucks; burning coal, oil, and other fossil fuels; and manufacturing chemicals. Millions of people live in areas where urban smog, very small particles, and toxic pollutants pose serious health concerns. Click here for cities on the map to find out more.

Carbon monoxide is an odorless, colorless gas and is formed when the carbon in fuels does not completely burn. Vehicle exhaust contributes roughly 60 percent of all carbon monoxide emissions nationwide, and up to 95 percent in cities. Other sources include fuel combustion in industrial processes and natural sources such as wildfires.

Why is air pollution a problem?

According to the Environmental Protection Agency, the average adult breathes over 3,000 gallons of air every day. Children breathe even more air per pound of body weight and are more susceptible to air pollution.

Air pollution threatens the health of human beings and other living things on our planet. While often invisible, pollutants in the air create smog and acid rain, cause cancer or other serious health effects, diminish the protective ozone layer in the upper atmosphere, and contribute to the potential for world climate change.

What is the difference between air pollutants and toxic air pollutants?

Toxic air pollutants (or Hazardous Air Pollutants) are different from air pollutants. Air toxics are known or suspected to cause cancer or other serious heath effects, such as damage to respiratory or nervous systems. Toxic air pollutants may exist as particulate matter or as vapors (gases). Air toxics include metals, particles, and certain vapors from fuels and other sources.

What is the air pollution index?

The Air Quality Index (AQI) is an index for reporting daily air quality. It measures how clean or polluted air is and informs the public to be aware of associated health concerns.

What pollutants affect air quality?

A few air pollutants, called criteria air pollutants, are common throughout the United States. These pollutants can injure health, harm the environment and cause property damage. The current criteria pollutants are: Carbon Monoxide, Lead, Nitrogen Dioxide, Ozone, Particulate matter with aerodynamic size less than or equal to 10 micrometers, and Sulfur Dioxide.

What can be done to prevent pollution?

Your home and office can actually contribute to the greenhouse effect. Energy used in everyday activities -- turning on electrical appliances, driving cars, and heating and cooling our homes -- is responsible for air pollution that contributes to climate change. You can cut down on pollution by:
  • Making sure your computer and monitor power management settings are optimized, so they go into sleep mode when you're away from your desk.
  • Making sure someone in your office turns off the printer and copier at the end of the day.
  • Setting your printers and copiers to automatically print on both sides -- it takes more energy to make a sheet of paper than to copy an image onto it.
  • To learn more about pollution:

    • Explore air pollution throughout the U.S., and find out which cities have the worst air quality with an interactive from

    • Click here for more information about air quality from the Environmental Protection Agency.

    • Read more about Energy Star, a joint program of the U.S. Environmental Protection Agency and the U.S. Department of Energy helping to protect the environment through energy efficient products and practices.

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