It's common for the Willamette Valley region to experience inversion
conditions that trap fine particle pollution near the ground. DEQ issues an air
pollution advisory when pollution levels rise and we expect an inversion to
persist for more than 48 hours. This advisory is primarily a health message to
protect sensitive individuals from adverse impacts from air pollution.
We're very concerned about people with heart or lung disease, older adults
and children because they're at greater risk from particles than other people,
especially when they're physically active. Exercise and physical activity cause
people to breathe faster and more deeply and to take more pollution into their
Inversions and pollution
Almost all fine particle pollution comes from combustion sources including
woodstoves and fireplaces, cars and trucks and diesel engines. Particle
pollution peaks in the late night and early morning hours. This is when
nighttime inversions trap pollutants at the earth’s surface. When DEQ issues an
air quality advisory, we generally see unhealthy levels in the late night and
early morning and then good or moderate levels for much of the day.
As the day warms up, the inversion tends to lessen or break, allowing the
pollution to mix out into cleaner air. When inversions last several days
however, pollution builds up and we start seeing persistently higher levels.
Symptoms people might experience
- People with heart disease could experience symptoms such as shortness of
breath or chest tightness.
- People with asthma or other lung problems may experience coughing, wheezing,
shortness of breath, bronchitis and increased asthma attacks.
- Since older adults are more likely to have preexisting lung and heart
diseases, they may be more susceptible to health effects from exposure to
- Children are susceptible to air pollution because their lungs are still
developing and they're often engaged in vigorous outdoor activities, making them
more sensitive to pollution than healthy adults. Children with pre-existing
illness or chronic conditions are at higher risk.
- People who smoke, especially those who have smoked for many years, generally
have reduced lung function and may be affected by dust and smoke exposure.
Smokers are also less likely to recognize and report symptoms from exposure to
irritant chemicals than nonsmokers.
- Don't exercise late at night or in the early morning hours. This is when
particle pollution peaks. We expect to see good or moderate levels during the
- If you have heart or lung diseases make sure you have adequate medication on
hand. If you have asthma, follow your asthma management plan.
- If you have symptoms of heart or lung disease like shortness of breath,
chest tightness or pain, or unusual fatigue, contact your health care provider.
Help reduce pollution
You can help reduce pollution by not using your fireplace or wood stove
during an air quality advisory. If this is your only source of heat, you can
still help by burning only dry wood in hot fires. Another way to help is to
drive less. For more information see EPA's brochure on Particle Pollution and Your Health.