Wildfires, weather causing poor air quality in WA. Which counties have the worst AQI?

Karlee Van De Venter, Shaun Goodwin
Smoke from two large wildfires near Spokane clogged the air near Palouse Falls State Park in Franklin County over the weekend. (Laurie Williams/Tri-City Herald)

A thick cloud of wildfire smoke is choking millions of Washington state residents due to 23 active wildfires in the state, in addition to the dozens of wildfires to the north in British Columbia.

Weather patterns influence the direction of where the smoke from wildfires goes, and right now, smoke is being pushed across all of Washington and into other parts of the Pacific Northwest by a southward wind from Canada.

The remnants of Hurricane Hilary and its associated wind have also pushed wildfire smoke from Idaho and Oregon into the Evergreen state. Some parts of the state, including around the Tri-Cities and Puget Sound, are at unhealthy air quality levels and are even approaching hazardous levels.

Washington’s Department of Ecology is responsible for running the state’s air monitoring network, which is a series of stations that monitor the air quality in a certain region. Here’s what to know about the air quality index or AQI, where you can get alerts for poor air quality, and the current air quality in every Washington county.

What is the Air Quality Index?

The AQI chart is a scale from 1 to 500 used to classify air quality levels using a formula and information of common pollutants in the air. A number is calculated daily unless there is an extreme condition, such as a wildfire, which results in it being updated more frequently.

The scale is divided into six sections, with various health risk and responses for each level:

  • Good - 0-50

  • Moderate - 51-100

  • Unhealthy for sensitive groups - 101-150

  • Unhealthy - 151-200

  • Very unhealthy - 201-300

  • Hazardous - 301-500

WA air quality by county

Air quality is reported by the U.S. Air Quality Index, as well as the Washington State Department of Ecology. County numbers are an average based on several cities’ most recently reported AQI, listed at 9:45 p.m. Aug. 22.

Unhealthy air quality for all

  • Chelan - 173

  • Grant - 159

  • Okanogan - 154

Unhealthy for sensitive groups

  • Ferry - 141

  • Stevens - 141

  • Yakima - 105

▪ Counties with moderate air quality

  • Adams - 100

  • Asotin - 70

  • Benton - 72

  • Columbia - 89

  • Franklin - 72

  • Garfield - 85

  • Lincoln - 68

  • Pend Oreille - 55

  • Spokane - 94

  • Walla Walla - 80

  • Whitman - 81

▪ Counties with good air quality

  • Clark - 22

  • Island - 19

  • Lewis - 19

  • Clallam - 23

  • Cowlitz - 20

  • Grays Harbor - 18

  • Jefferson - 18

  • King - 27

  • Kittitas - 47

  • Klickitat - 13

  • Mason - 15

  • Pacific - 15

  • Pierce - 22

  • San Juan - 19

  • Skagit - 19

  • Skamania - 15

  • Snohomish - 30

  • Thurston - 18

  • Wahkiakum - 20

  • Whatcom - 22

What makes air unhealthy?

Air quality monitors record ground-level ozone pollution, particle pollution, carbon monoxide, sulfur dioxide, lead and nitrogen dioxide, which are all required to be monitored under the Clean Air Act.

Each criterion pollutant can uniquely contribute to harmful health effects and negative environmental consequences.

Particle pollution is often a result of wildfires. A study published by the governmental agency AirNow discovered that “wildfires contribute 15 to 30% of atmospheric primary fine particulate matter emissions in the United States”.

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