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EPA’s Six Criteria Pollutants

An Overview – The air we breathe in many U.S. cities is being polluted by activities such as driving cars and trucks; burning coal, oil, and other fossil fuels; and manufacturing chemicals. Air pollution can even come from smaller, everyday activities such as dry cleaning, filling your car with gas, and degreasing and painting operations. These activities add gases and particles to the air we breathe. When these gases and particles accumulate in the air in high enough concentrations, they can harm us and our environment. More people in cities and surrounding counties means more cars, trucks, industrial and commercial operations, and generally means more pollution.

Air pollution is a problem for all of us. 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. Many air pollutants, such as those that form urban smog and toxic compounds, remain in the environment for long periods of time and are carried by the winds hundreds of miles from their origin. Millions of people live in areas where urban smog, very small particles, and toxic pollutants pose serious health concerns. People exposed to high enough levels of certain air pollutants may experience burning in their eyes, an irritated throat, or breathing difficulties. Long-term exposure to air pollution can cause cancer and long-term damage to the immune, neurological, reproductive, and respiratory systems. In extreme cases, it can even cause death1.

The Environmental Protection Agency (EPA) has set National Ambient Air Quality Standards (NAAQS) for six common air pollutants. Also known as “criteria pollutants”, these commonly found air pollutants are found all over the United States. They are:

  • Particle Pollution (particulate matter)
  • Ground-level ozone
  • Carbon monoxide
  • Sulfur oxides
  • Nitrogen oxides
  • Lead

The EPA calls these pollutants “criteria” air pollutants because it regulates them by developing human health-based and/or environmentally-based criteria (science-based guidelines) for setting permissible levels. Primary standards are limits based on the human health, secondary standards are limits intended to prevent environmental and property damage.

The National Ambient Air Quality Standards for the above-mentioned criteria pollutants are listed below. Units of measure for the standards are parts per million (ppm) by volume, milligrams per cubic meter of air (mg/m3), and micrograms per cubic meter of air (μg/m3).

National Ambient Air Quality Standards
Pollutant Primary Stds. Averaging Times Secondary Stds.
Carbon Monoxide 9 ppm
(10 mg/m3)
8-hour (1) None
35 ppm
(40 mg/m3)
1-hour(1) None
Lead 1.5 μg/m3 Quarterly Average Same as Primary
Nitrogen Dioxide 0.053 ppm
(100 μg/m3)
Annual (Arithmetic Mean) Same as Primary
Particulate Matter (PM10) Revoked(2) Annual(2) (Arith. Mean) Revoked(2)
150 μg/m3 24-hour(3) Same as Primary
Particulate Matter (PM2.5) 15.0 μg/m3 Annual(4) (Arith. Mean) Same as Primary
35 μg/m3 24-hour(5) Same as Primary
Ozone 0.08 ppm 8-hour(6) Same as Primary
0.12 ppm 1-hour(7)
(Applies only in limited areas)
Same as Primary
Sulfur Oxides 0.03 ppm Annual (Arith. Mean) ——-
0.14 ppm 24-hour(1) ——-
——- 3-hour(1) 0.5 ppm
(1300 μg/m3)

(1) Not to be exceeded more than once per year.

(2) Due to a lack of evidence linking health problems to long-term exposure to coarse particle pollution, the agency revoked the annual PM10 standard in 2006 (effective December 17, 2006).

(3) Not to be exceeded more than once per year on average over 3 years.

(4) To attain this standard, the 3-year average of the weighted annual mean PM2.5 concentrations from single or multiple community-oriented monitors must not exceed 15.0 µg/m3.

(5) To attain this standard, the 3-year average of the 98th percentile of 24-hour concentrations at each population-oriented monitor within an area must not exceed 35 µg/m3 (effective December 17, 2006).

(6) To attain this standard, the 3-year average of the fourth-highest daily maximum 8-hour average ozone concentrations measured at each monitor within an area over each year must not exceed 0.08 ppm.

(7) (a) The standard is attained when the expected number of days per calendar year with maximum hourly average concentrations above 0.12 ppm is < 1, as determined by appendix H.
(b) As of June 15, 2005 EPA revoked the 1-hour ozone standard in all areas except the fourteen 8-hour ozone nonattainment Early Action Compact (EAC) Areas.

* The information provided above is referenced from: http://www.epa.gov/air/criteria.html

1-Referenced from: http://www.epa.gov/air/basic.html

Ways to Reduce Air Pollution – We make choices everyday that can help reduce air pollution. Below are a few ideas that you can take to help clean our air.

At Home

  • Conserve energy – turn off appliances and lights when you leave the room.
  • Recycle paper, plastic, glass bottles, cardboard, and aluminum cans. (This conserves energy and reduces production emissions.)
  • Keep woodstoves and fireplaces well maintained. You should also consider replacing old wood stoves with EPA-certified models. Visit http://www.epa.gov/woodstoves.
  • Plant deciduous trees in locations around your home to provide shade in the summer, but to allow light in the winter.
  • Buy green electricity-produced by low-or even zero-pollution facilities.
  • Connect your outdoor lights to a timer or use solar lighting.
  • Wash clothes with warm or cold water instead of hot.
  • Lower the thermostat on your water heater to 120°F.
  • Use low-VOC or water-based paints, stains, finishes, and paint strippers.
  • Test your home for radon-a dangerous, radioactive gas that is odorless and tasteless. If the test shows elevated levels of radon, the problem can be fixed cost effectively. Visit http://www.epa.gov/radon.
  • Choose not to smoke in your home, especially if you have children. If you or your visitors must smoke, then smoke outside. Visit http://www.epa.gov/smokefree.

Buy Smart

  • Buy ENERGY STAR products, including energy efficient lighting and appliances. They are environmentally friendly products. For more information, visit http://www.energystar.gov or call 1-888-STAR-YES.
  • Choose efficient, low-polluting models of vehicles. Visit http://www.epa.gov/greenvehicles.
  • Choose products that have less packaging and are reusable.
  • Shop with a canvas bag instead of using paper and plastic bags.
  • Buy rechargeable batteries for devices used frequently.

Drive Wise – Plan your trips. Save gasoline and reduce air pollution.

  • Keep tires properly inflated and aligned.
  • In the summertime, fill gas tank during cooler evening hours to cut down on evaporation. Avoid spilling gas and don’t “top off” the tank. Replace gas tank cap tightly.
  • Avoid waiting in long drive-thru lines, for example, at fast-food restaurants or banks. Park your car and go in.
  • When possible, use public transportation, walk, or ride a bike.
  • Get regular engine tune ups and car maintenance checks (especially for the spark plugs).
  • Use an energy-conserving (EC) grade motor oil.
  • Ask your employer to consider flexible work schedules or telecommuting.
  • Report smoking vehicles to your local air agency.
  • Join a carpool or vanpool to get to work.

For Your Health

  • Check daily air quality forecasts, which tell how clean or polluted your air is, and the associated health concerns. Visit http://www.airnow.gov/
  • Remove indoor asthma triggers from your home and avoid outdoor triggers in order to effectively control your asthma. Visit http://www.epa.gov/asthma/ to learn more about asthma triggers and ways to avoid them.
  • Minimize your sun exposure. Wear sun block and UV protection sunglasses. To find out about current forecasts of UV where you live, go to http://www.epa.gov/sunwise/uvindex.html.

*The information provided above is referenced from: http://www.epa.gov/air/oaq_caa.html/peg/reduce.html

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