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Air Quality Index (AQI)

The federal Air Quality Index (AQI) is a number that shows how good (or bad) the air quality is. We use AQI information to advise you about air quality levels. When there is too much air pollution, your health could be at risk.

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Using the Air Quality Index

The AQI tells us if the air is polluted.  It gives us information about how recent levels measured in the air relate to health problems.  The bigger the number, the more pollution in the air and the higher the risk for health problems.

The AQI measures these air pollutants (called criteria air pollutants):

The table shows the possible health effects of air quality at different levels. Each level is a different color with its own set of health problems.

Color (Values)

Meaning – What You Can Do

Green dot Green
        (0-50)

Good – Air pollution is low.

  • There is little health risk.
  • Make a plan if air quality is forecasted to get worse.

Yellow dot Yellow
        (51-100)

Moderate – Some people are more sensitive to lower levels of particle pollution. These people should:

  • Spend less time outside.
  • Reduce strenuous outdoor activity.
  • Watch for symptoms to reduce your exposure.

Orange dot Orange
        (101-150)

Unhealthy for sensitive groups (USG) – Sensitive groups should:

  • Spend less time outside.
  • Reduce strenuous outdoor activity.
  • Watch for symptoms to reduce your exposure.

Red dot Red
        (151-200)

Unhealthy –  Everyone should reduce exposure.

  • Spend less time outside.
  • Reduce strenuous outdoor activity.
  • Watch for symptoms to reduce your exposure.
  • Follow tips for cleaner indoor air. 

Purple dot Purple
       (201-300)

Very unhealthy – Everyone should reduce exposure.

  • Avoid outdoor activity.
  • Stay inside. Filter indoor air to keep it cleaner. Make your own clean air fan.
  • Go somewhere else for cleaner air, if you need to.

Dark Red dot Dark red
       (301+)

Hazardous – Everyone should reduce exposure.

  • Stay inside. Filter indoor air to keep it cleaner. Make your own clean air fan.
  • Do only light indoor activities.
  • Keep windows and doors closed if it's not too hot.
  • Go somewhere else for cleaner air, if you need to.
  • If you must be outside, wear an N95 mask.


Washington's Air Monitoring Network

Ecology and other clean air agencies maintain monitoring stations to measure air pollution in Washington. The map below displays current AQI levels. Find a bigger map with more features at Washington Air Quality Map.

Go to Washington Air Quality map for a bigger map with more features.

Air quality mobile app

Download the air quality mobile app:

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Contact information

Matt Kadlec
Toxicologist
matt.kadlec@ecy.wa.gov
360-522-0701