Be aware of the air: Wood Smoke monitoring begins Oct. 1

September 25, 2019

Beginning Oct. 1 homeowners, renters and businesses in Multnomah County cannot use wood stoves, fireplaces or burn outdoors on days when the air quality is forecasted to be poor. This includes:

  • Wood stoves

  • Fireplaces

  • Outdoor fire pits

  • Chimeneas

Multnomah County’s winter wood smoke ordinance is in effect Oct. 1 through March 1.

Nadège Dubuisson coordinates Multnomah County's winter wood smoke ordinance.

Wood burning is allowed for people who use wood exclusively to heat their homes and those with limited incomes. The use of wood stoves are also permitted during emergencies such as a power outage. And, there are no restrictions on wood or charcoal used for cooking.

Wood smoke is regulated during the cooler months because wood smoke from home heating accounts for more than half of our fine particle pollution on the average winter day. The air quality can be especially poor during days of still air and temperature inversions — when cold air is trapped close to the earth.

The rule helps protect people who are most vulnerable to poor air quality — children, seniors and people with asthma and other serious breathing conditions. The rule also helps keep the Portland region in compliance with national air quality standards.

“Our air shed has gotten close to exceeding the legal limits of particulates, and that pollution can make medically vulnerable people sicker,” said Environmental Health Director Jae Douglas, Ph.D. “Most people are surprised when they learn what big role wood smoke plays in winter air quality. I love having a fire on cold nights, But when the air quality is already bad, I’m willing to forgo that to help my neighbors breathe easier.”

How it Works

From Oct. 1 through March 1, officials at Multnomah County Environmental Health will conduct daily forecasting in cooperation with the Department of Environmental Quality and the National Weather Service to identify potential poor air quality days.

When conditions suggest more pollution and an upcoming inversion (which cause air to become stagnant and trap pollutants close to the ground), Multnomah County will announce a burn restriction by 11 a.m. The curtailment will go into effect at noon and remain in effect for 24 hours, unless an extension is warranted.

Officials will publish mandatory curtailment notices on the county’s Wood Smoke website, share the notice through social media, including Facebook and Twitter, and push out the notice on Public Alerts (sign up here).

Residents can also sign up to receive emails on all voluntary and mandatory curtailment notices. 

On most days, a dial posted on the website will point to Green — “Air quality is good. No burn restrictions.”

On some days, the dial might show an arrow pointed to Yellow — “Air quality is moderate,” suggesting a voluntary curtailment for that day.

Rarely, when air quality and weather is very bad, that same dial will point to Red — “Air quality is unhealthy. Burn restriction.”

During a curtailment period, residents can report a suspected violation to Environmental Health by calling 503-988-0035 or emailing

Why we need a rule

This is the second full year of Multnomah County’s Wood Smoke Ordinance. Last year, officials issued 21 “Yellow Day” voluntary curtailments and two “Red Day” burn restrictions.

The county received seven complaints on restricted burning days, and sent those households warning letters and informational packets on the county ordinance and the health effects of wood smoke pollution. The county issued no fines.

“This ordinance is still pretty new to folks,” said Environmental Health Specialist Nadège Dubuisson. “The goal is primarily to raise awareness that wood smoke is a real health issue and to prevent additional air pollution during our coldest and dreary months. Our biggest ask is that you check the air quality before having a fire.” 

Environmental Health Director Jae Douglas, Ph.D. Talks to residents in East Multnomah County about the wood burning ordinance in Nov., 2017

Poor air quality disproportionately affects children, seniors and people with existing health conditions. Short-term exposure to wood smoke can aggravate asthma, bronchitis and lung disease. And long-term exposure has been linked to cancer and higher rates of infant mortality.

After cars and truck emissions, residential wood smoke is the largest contributor to cancer risk from air pollution. Area wood stoves, pellet stoves, and outdoor fires account for 11 percent of total cancer risk from air pollution, while industrial emissions account for about one percent of the county’s excess cancer risk from air pollution.

[View Multnomah County’s air toxics and cancer risk assessment]

Multnomah County’s rule represents an effort to remain in compliance with federal laws as the population grows. The Environmental Protection Agency regulates six air pollutants including particulate matter. In recent years the airshed that includes Multnomah County has come close to exceeding its limit on particulate matter 2.5. Washington County, Eugene, Medford, Klamath Falls and Pendleton have all passed similar ordinances as local jurisdictions struggle to remain in compliance with federal air pollution limits.

If you must burn, follow these four easy steps to help reduce the output of harmful wood smoke:

  • Burn dry, seasoned wood that has been split, stacked, covered and stored.

  • Test wood with a moisture meter before burning (20% moisture or less is best).

  • Use a cleaner-burning EPA or DEQ-certified gas or wood stove.

  • Burn small, hot fires. Provide sufficient air to the fire; never let it smolder.

Learn more about what you can do to reduce wood smoke at