Air quality advisories

High pollution and ozone air quality advisories and forecasts
We provide advisories and forecasts statewide daily through: 
  • 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.
  • Our Colorado Air Quality Advisory Forecasts website.
  • Our Facebook and Twitter streams.
  • An email Listserv to subscribers.
Action Days
  • When conditions warrant, the forecast will call for an Action Day.
  • An Action Day for fine particulates, carbon monoxide or ozone indicates 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 mean air quality will be in the Unhealthy or Unhealthy-for-Sensitive-Groups categories, according to the Air Quality Index.
  • In the seven-county metro Denver area, Action Days trigger mandatory residential burning restrictions during the winter months, voluntary driving reductions and public health recommendations.
  • Residential burning restrictions apply between Nov. 1 and March 31.
Ozone advisories
  • Ozone advisories statewide occur both in summer and winter, though in the Denver area they’re more common in summer.
  • When ground-level ozone concentrations are expected to reach unhealthful levels, our forecasts will indicate an Action Day for ozone is in effect.
    • We then encourage voluntary reductions in driving, lawn mowing, painting and other activities that release ozone-forming hydrocarbons and volatile chemical compounds.
  • 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.