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Air Quality Advisories


High Pollution and Ozone Air Quality Advisories and Forecasts




The Planning and Policy Program works with the Technical Services Program to issue air quality advisories and forecasts statewide. The advisories and forecasts are provided daily through the following means:


  • media outlets that announce the advisories or place the above graphic on their websites
  • recorded messages on telephone hotlines
    • 303-782-0211
    • 303-758-4848
  • Through our Colorado Air Quality Advisory Forecasts  website
  • Through our Facebook and Twitter sites
  • Through an email listserv to subscribers


When conditions warrant, the forecast will call for an "Action Day". An "Action Day" for fine particulates, carbon monoxide or ozone indicates either that current air quality is unhealthful or conditions are expected to worsen later in the day or on the next day. "Action Days" for air pollutants generally indicate that air quality will either be in the Unhealthy or Unhealthy-for-Sensitive-Groups categories (according to the Air Quality Index).

In the seven-county Denver-Boulder metropolitan area, Action Days trigger mandatory residential burning restrictions during the winter months, voluntary driving reductions and public health recommendations. Residential burning restrictions apply between November 1 and March 31.



Ozone Advisories

Ozone advisories statewide occur both in the summer and winter, though they are more common in the summer in the Denver area.  When ground-level ozone concentrations are expected to reach unhealthful levels, forecasts will indicate that an "Action Day" for ozone is in effect. The state then encourages voluntary reductions in driving, lawn mowing, painting, and other activities that create ozone-forming hydrocarbons and volatile chemicals.


When no "Action Day" is indicated, air quality is good or moderate and is expected to remain so during the effective period of the forecast. No restrictions are in place.



Follow the Advisories and Forecasts


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