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Air Quality

Air Pollution Advisories

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Air Pollution and Health Problems

If you suffer from heart or lung disease, follow your doctor's advice on how to care for your condition on days when air pollution is increasing. You can reduce your risk by avoiding strenuous activity during the time when air pollution is worst, usually between 3 p.m. and 6 p.m.

Smog and ozone

When we talk about smog, we are referring to ground-level ozone. This can be confusing, since we also talk about ozone — the ozone layer — as something we want to save. The ozone layer occurs high in the earth's stratosphere and protects the earth from the sun's harmful ultraviolet light. Ozone in this layer is created and destroyed naturally all the time, though many man-made chemicals aid in the destruction. Ground-level ozone closer to the earth's surface can harm the health of people, animals and plants

Ground-level ozone is also called smog. Smog-forming pollutants are primarily generated by traffic and activities in urban areas, but often the wind blows the pollution to outlying suburban and rural communities.

Smog is a problem for the Portland-Vancouver and Medford areas during the summer months. It is created most often on days when the temperature is 90 degrees or higher, especially when winds are light or non-existent.

Weather is one of the key factors in smog formation. While we can't control the weather, we can take steps to reduce smog. Eighty percent of air pollution comes from everyday activities. If each person does just one thing to reduce pollution it will make a big difference in the air we breathe.

The effects of smog exposure can be compared to a sun burn on the lungs and, even at low levels, can lead to:

  • Asthma attacks
  • Aggravation of chronic lung diseases, emphysema and bronchitis
  • Coughing, chest pain, difficulty breathing deeply
  • Itchy, burning eyes

Smog can affect children, people with heart and lung diseases and older people. Children are especially at risk because their lungs are still developing and they spend more time outside in the summer when ozone levels are highest. Even healthy people can be affected if they exercise outdoors.

Smog mars our mountain views. On hot, stagnant days, we often have a brown, hazy ring around Mt. Hood and other mountains in the Portland-Vancouver area. The U.S. Forest Service reports that smog-related pollution has damaged trees, moss and lichen in Pacific Northwest forests.

Smog also affects economic growth in the Portland-Vancouver region. If we exceed the federal health standard for smog more than three times in three years, we will not maintain our status as a "clean air region." Our region could potentially experience the stigma of dirty air and expensive new regulatory requirements. New businesses may not locate in the region and existing businesses would face tougher requirements for expansion.


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Oregon Department of Environmental Quality
Headquarters: 700 NE Multnomah Street, Suite 600, Portland, OR 97232
Phone: 503-229-5696 or toll free in Oregon 1-800-452-4011
Oregon Telecommunications Relay Service: 1-800-735-2900  FAX: 503-229-6124

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the State of Oregon and the Environmental Protection Agency.

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