Seattle, Washington, and Portland, Oregon, are experiencing some of the worst air quality issues in the world due to fires, out-ranking cities in China, Italy, and Czech Republic.
According to IQAir, a Swiss tech company that tracks air quality levels around the world in real time, Seattle was at the top of the list as of Thursday afternoon with an air quality index (AQI) of 226. This puts the city under the "very unhealthy" category based on the Environmental Protection Agency's measurement standard.
IQAir pulls AQIs from various sources including regional government agencies that track air quality.
Sitting below Seattle, with an AQI of 183 or "unhealthy" air quality levels as of Thursday afternoon, is Portland.
Both cities are experiencing poor air quality issues due to large fires.
East of Seattle, near Skyomish, Washington, is the Bolt Creek Fire, which burned about 14,000 acres of forest during the week. According to KUOW, the fire was human-sparked and continues to burn.
About 20 miles northeast of Portland, the Nakia Creek Fire in Clark County, Washington, burned about 1,600 acres by Monday, according to The Washington Post.
The poor air quality issues in both cities are expected to subside by this week, according to IQAir.
According to the Swiss air tracking company, the top cities with the worst air quality year-round between 2018 and 2021 were located in Asian countries, including India, China, and Pakistan. Some of the cities are in close proximity to each other, and the rankings are based on levels of particulate matter that was found in the air.
Based on that measurement, more than 300 cities had pollutants in their air that exceeded recommendations from the World Health Organization by seven to 10 times.
Here are the top 10 cities that had the worst air quality in the world in 2021: