Portland Air quality today

What happened to Portland's air in September 2020?

The Air Quality Index, or AQI, runs from 0 to 500, and anything from 301 to 500 is hazardous for everyone ^[2]. Before 2020, Portland's daily record for wildfire season was an AQI of 157, in the unhealthy range, set in 2017 ^[2]. On Sunday, September 13, 2020, wildfire smoke set a new record of 477, about three times as high ^[2].

In that week of September 2020, Portland had two hazardous days and two very unhealthy days ^[2]. Before then, Portland had never had a very unhealthy day ^[2]. The release noted that the 2020 data was preliminary and not yet validated by Oregon DEQ, the state environment agency ^[2].

Where does the smoke and pollution come from?

Wildfire smoke is made of gases and fine particles that travel long distances ^[4]. The Oregon Health Authority says smoke can travel hundreds or thousands of miles ^[5]. Scientists are concerned about PM2.5, particles 2.5 microns across or smaller; thirty of them in a row are as wide as a human hair ^[5].

In winter, much of the pollution is local. In 2021, Multnomah County said wood smoke from home heating makes up more than half of its fine particle pollution on an average winter day ^[3]. Air quality can be especially poor on still days with a temperature inversion, when cold air is trapped close to the ground ^[3].

Ozone, also called smog, is a different problem. It forms when gases from tailpipes, smokestacks and factories react with sunlight ^[1].

How does Portland compare with other US cities?

In the American Lung Association's 2026 State of the Air report, based on 2022 to 2024 data, the Portland-Vancouver area ranked 186th worst for year-round particle pollution ^[1]. That tied it for 23rd best among the cleanest US cities ^[1].

Its other rankings were worse. The area ranked 101st worst for short-term particle pollution, with 1.8 unhealthy days a year in its worst county, Clark County, Washington ^[1]. It ranked 84th worst for ozone, with 2.7 unhealthy days a year and a D grade in Clackamas County, Oregon ^[1]. The report said air quality in the area worsened slightly ^[1].

What is Multnomah County doing about wood smoke?

Multnomah County has a wood smoke rule. As described in 2021, it ran each year from October 1 through March 1 ^[3]. On days when poor air is forecast, a yellow day asks people not to burn, and a red day bans wood stoves, fireplaces and outdoor fire pits ^[3]. People who heat only with wood or have limited incomes can apply for an exemption, and cooking with wood or charcoal is not restricted ^[3].

In February 2022, the county board extended the rule to the whole year ^[4]. On August 26, 2023, wildfire smoke over the Portland metro area led to a red day ^[4]. It was the sixth warm-season red day since the change, and the earlier ones were for ozone on hot days ^[4].

How to protect yourself in Portland

When smoke is forecast, check your state or local air quality agency or the AirNow Fire and Smoke Map ^[6]. Stay inside with doors and windows closed, and set any cooling system or car ventilation to recirculate ^[6][5]. Run a portable air cleaner that suits the room size and makes little or no ozone, and keep one room as a cleaner air room ^[6].

Do not add to indoor pollution on smoky days. Skip candles, incense, wood stoves and fireplaces, and avoid long, high-heat cooking ^[6]. Outdoors, avoid hard exercise such as running or mowing ^[6]. Cloth, dust and surgical masks do not protect against smoke particles; a well-fitted N95 respirator can, but it does not suit young children ^[5][6].

Older adults, babies and children, pregnant people, and people with long-term heart or lung disease are more sensitive to smoke ^[5]. If you have a long-term heart or lung condition, follow your treatment plan and call your health care provider if smoke makes it worse ^[5].