Pictured: Wildfires burning across Washington, Oregon and California, have resulted in far-reaching PM2.5 pollution from across the US to Canada and eastward for thousands of miles, heat-mapped here in US AQI colors. Source: IQAir Earth

In September 2020, millions in the Northwest saw their skies turn red with smoke and fled from dangerous air quality conditions across Oregon, Washington, and British Columbia.

At various points, three of the region’s major cities topped the IQAir live air quality and pollution city ranking: Portland, Seattle, and Vancouver, each of which saw record air pollution well into the “very unhealthy” range above 200 – increasing the risk of health effects for anyone exposed to air pollution from wildfire smoke in these cities.

IQAir Map databases, powered by over 80,000 sensors worldwide, helped demonstrate just how widespread the air quality impact from these wildfires hadbeen to over 9 million in the Pacific Northwest over a period of weeks.

Air quality impact of Northwest wildfires

Several wildfires erupted throughout the state of Washington on Monday, September 8. Fanned by 50 mile-per-hour winds and fueled by an abundance of dry timber, the fires burned through more than 580,000 acres in less than 72 hours.¹

Washington wildfire smoke presentedthe greatest risks to:

• Seattle air quality: Reached a high daily average U.S. air quality index (AQI) of196 on Friday, September 11, more than 2.5 times the WHO daily target for exposure to PM2.5 (particulate matter with a diameter size of 2.5 microns or smaller).
• Olympia air quality: Reached a high daily average of AQI 168 on Friday, September 11.
• Tacoma air quality: Reached a high daily average of AQI 182 on Friday, September 11.
• Vancouver, Canada air quality: Reached a high daily average of AQI 227 on Sunday, September 13th.

Dozens of fires ravagedOregon’s forested valleys and coastlinesin what may become the state’s deadliest and most destructive wildfire season yet.² More than 3,000 firefightersworkedthe frontlines of Oregon’s 48 blazes, whichburned through more than 500 square miles, or more than 320,000 acres.

Oregon wildfire smokepresentedthe greatest risks to:

• Eugene air quality: Reached a high daily average of AQI 384 “hazardous” on Tuesday, September 8, more than 13 times the WHO daily target for PM2.5 exposure. Hazardous air quality was sustained on Wednesday September 9, with a daily average AQI of 331.
• Salem air quality: Reached a high daily average of AQI 487 on Saturday, September 12. Hourly AQI measurements above 160 were sustained for 14 hours on Tuesday, September 8 before dropping to “moderate” levels in the evening.
• Portland air quality: Reached a high daily average of AQI 357 on Monday, September 7. Air pollution levels in Portland stayed above the 200 “unhealthy” AQI threshold for 7 consecutive days, including three straight days above 300 (“hazardous”) before falling back into the high 100s.

How do I interpret IQAir wildfire air quality data?

IQAir Map provides a large-scale visualization showing the air quality impact of wildfire smoke as well as allowing you to locate active fires in your state and understand the effect wind has on transporting toxic wildfire air pollutants across many miles.

These visualizations are generated from an aggregation of real-time, hyperlocal air quality data from thousands of air quality monitors fromgovernment and community-based air quality monitors in the affected states that contribute to the AQI measurements shown on our maps. These readings represent an incredibly precise measurement of the level of air pollution you’re exposed to and how dangerous this pollution is to your health.

Air quality data is updated hourly – this helps avoid transmitting inaccurate fluctuations in the data that happen over the course of the hour and result in incorrect readings common in many other air quality monitors and sensors. The data is also compared against readings from nearby sensors to ensure that data is consistent across the geographical location.

Active fire data is integrated from NASA's Fire Information for Resource Management System (FIRMS) and is updated every three hours. Fire locations are indicated with icons placed at the exact coordinates while air quality data is reported from governmental and community-contributed air quality monitors, modelized in real time, updated hourly.

IQAir Map also allows you to see real-time air quality readings from AirVisual sensors – represented as an AQI number, the reading from each monitor represents highly accurate data from an exact location that can be furtherexamined for historical and forecast data up to 72 hours.

Pictured: Real-time AQI measurements from IQAir AirVisual air quality sensors across California and the Pacific Northwest during major wildfires in September 2020. At the time, Portland was the most polluted major city in the world, followed closely by Vancouver at number two and Seattle at number 6. Source: IQAir Map

See live air quality data from air quality monitors in major cities throughout your state, plus thousands more hyperlocal air quality sensors in neighborhoods, communities, and other regions within those cities:

• Oregon – over 225 real-time city air quality monitors
• Washington – over 400 real-time city air quality monitors
• British Columbia – over 117 real-time city air quality monitors

Washington wildfires

Before 2020, 2015 was the state's most destructive wildfire season, with 500,000 burned acres. 2020 bested this record in three days.

Pictured: Wind fans air pollution from wildfires across the state of Washington (Wednesday, September 9, 12pm PST). Source: IQAir Map

Of the 37 active fires thatburnedin Washington on Tuesday, September 9, the two largest werethe 174,000-acre Pearl Hill Fire, in Douglas County, and the 163,000-acre Cold Springs Fire near Omak.³

Three fires in Whitman County quickly burned 32 square miles, or more than 20,000 acres, including:⁴

• The Malden-Babbs Fire: 17,781 scorched acres, (see the live air quality impact near the Malden-Babbs fire in Rosalia, WA)
• The Manning Fire: 3,063 scorched acres, (see the live air quality impact near the Manning Fire in Lacrosse, WA)
• The Colfax Fire: 5 scorched acres, (see the live air quality impact of the Colfax Fire near the neighboring city of Moscow, ID)

The small town of Malden, Washington, which belongs to Whitman County, was almost completely leveled on Tuesday, with roughly 80 percent of its structures destroyed. Pine City also suffered significant damage. The most recent report estimates that these three fires burned 91 homes, 8 commercial properties and 90 other structures within a matter of days.

Public Lands Commissioner Hillary Franz described the situation as“one of the worst nightmares we can imagine.”

More than 1,500 firefighters were on the frontlines, fighting wildfires in every corner of the state. The National Guard was called on to assist, though resources were spread thin with devastating wildfires burning in California, Oregon, and Colorado.

The Cold Springs fire resulted in one death.⁵

Impact on air quality

Easterly winds carried plumes of smoke from wildfires toward the Puget Sound area where most of the state’s population resides. More than 5 million residents were exposed to air pollution levels classified as “unhealthy” for the general public for over two weeks.

On September 8th, around 12 p.m. local time, Seattle topped the IQAir major city ranking for worst air pollution globally with an air quality index of 193. Seattle largely held its position in the top ten for 48 hours, continually beating notorious New Delhi air quality and Beijing air quality for highest overall AQI.**

Washington wildfires in the western and northernmost part of the state have also affected air pollution levels in Canada, with some smoke carried more than 200 miles from the source. On Tuesday September 8, air quality levels in Richmond, Canada and Vancouver, Canada hit highs of AQI 150+, “unhealthy.”

Wildfires release a range of air toxins including particulate matter (PM2.5 and PM10), carbon monoxide, and nitrogen dioxide. Among these, fine particulate matter, or PM2.5, is most often present at the riskiest levels to health.

PM2.5 is airborne matter measuring 2.5 micrograms or smaller, such as near microscopic particles of dust, soot and ash. It is categorized by its size, rather than its chemical composition because PM2.5 is so small, it can penetrate deep into the lungs, and even into the circulatory system, causing far reaching health effects. Exposure to PM2.5 has been linked to adverse health effects including chest pain, arrhythmias, bronchitis, heart and lung disease, cancer and early death.

The US Environmental Protection Agency (EPA) uses an air quality index (AQI) to translate pollutant concentrations to a relatable scale for risk to health. The scale ranges from 0 to 500, where 0 to 50 is considered “good,” 51 and 100 is “moderate,” 101 to 150 is “unhealthy for sensitive groups,” 151 to 200 is “unhealthy,” 201 to 300 is “very unhealthy,” and 301 to 500 is considered “hazardous.”

Pictured: Hourly air quality index levels for Seattle, from 9 p.m. Monday, September 7 to 8 p.m. Wednesday, September 9.

Reduce your air pollution exposure in Washington state by following the wildfire protocol advised below:

• Stay current with real-time and forecast air quality conditions: air pollution is fast-changing and dynamic, particularly when originating from active wildfires. It’s important to stay informed of the changing risks in the air to guide exposure-reducing actions.
• Take action when AQI levels exceed 100: close windows and doors and seal door gaps and window cracks. Set air conditioning (HVAC) systems with fresh air intake to their recirculate mode. Use air purifiers or high-efficiency HVAC filters to remove fine particles from the air. Run the air cleaning systems as often as possible, on the highest fan speed.
• Avoid strenuous outdoor activity: reduce the amount of smoke you inhale by slowing down activity and controlling the rate of inhalation (e.g. walk, don't run). Wear an N95 pollution mask if possible when outdoor air exceeds AQI 150.
• Evacuate when necessary: when air quality levels become “very unhealthy” or "hazardous" and are expected to remain unhealthy for several hours, evacuate if possible. Use the air quality forecast provided on IQAir’s city and station pages to guide evacuation decisions.

Oregon wildfires

High winds have whipped flames across thousands of acres, making firefighting difficult. Governor Kate Brown tweeted on September 9^th“Our number-one priority right now is saving lives.”

Pictured: Air quality levels from “unhealthy” to “hazardous” stretch across the Oregon coastline (Thursday, September 10, 7am PST).Source: IQAir Map

The town of Detroit in the Santiam Valley, Blue River and Vida in coastal Lane County, and Phoenix and Talent in southern Oregonhave been substantially destroyed, according to Gov. Brown.

September 8^th and 9^th have had strong 50 mile-per-hour easterly winds blowing west. Normally, however, wind blows in from the Pacific Ocean at gentler speeds.

Fires including the Holiday Farm, Almeda Drive, and Archie Creek fires across the state resulted in at least 12 injuries and 5 deaths in September.^6,7,8

Impact on air quality

The quantity and close proximity of Oregon’s wildfireshad dramatic effects on the air quality of Oregon’s largest coastal cities. Images of red skies and less than 10 feet of visibility were shared widely across the internet.

Eugene notably, a city of 170,000, saw its air quality reading “very unhealthy” or worse for three days in a row September 7^th through 9^th. September 8^th and 9^thaveraged “hazardous” air quality readings, with AQIs of 384 and 331 respectively.

Pictured: Hourly air quality index (AQI) data for Eugene, Oregon from Tuesday morning, September 8 to Thursday morning, September 10.

Dangerous levels of air pollution persisted throughout the region until the fires were contained.

Follow live air quality advisories across the state for pertinent health information. When air quality levels reach “very unhealthy” or worse, consider evacuating to reduce your health risk. Sensitive individuals such as children under 18, adults over 65, and those with heart and lung disease are particularly vulnerable to adverse effects from air pollution.

**The IQAir major city ranking features 100 major cities with a population of more than 300,000 people, which represent a wide range of countries to allow global contrast. The ranking is updated hourly and is based on a comparative level of air quality across major cities at any given hour. To compare cities using their annual mean air quality levels, visit IQAir’s World’s Most Polluted Cities list.