Overview of Colorado’s Air Quality Index Reporting, Forecasting, and Advisory Program

Air Quality Index

Air Quality Index Scale

  • The Colorado Department of Public Health and Environment (CDPHE) Air Pollution Control Division (APCD) Technical Services Program (TSP) reports the Air Quality Index (AQI) to the public every hour of the day using air quality measurements from continuous (real time) monitors at stations located around the state.
  • The AQI is a federal index for reporting air quality. It indicates how clean or polluted the air is, and what associated health effects might be a concern. The AQI focuses on health effects a person may experience within a few hours or days after breathing polluted air. For more about the Air Quality Index, visit:
  • At least once a day (year-round), APCD/TSP air quality meteorologists issue Air Quality Index (AQI) forecasts for today and tomorrow (and sometimes for extended periods) for defined forecast areas. Forecasts may be revised anytime due to changing conditions.
    • As of August 2013, the defined AQI forecast areas include the Denver Metro area, Fort Collins, Greeley, Colorado Springs, Grand Junction, the Colorado River Valley, and the Four Corners area.
    • Currently, daily AQI forecasts are issued only in areas with continuous (real time) monitors.
  • AQI reports/forecasts are available at and
  • In addition to AQI forecasts, air quality advisories are often issued when the AQI exceeds (or is expected to exceed) a value of 100; or, in areas without air quality monitors, when there is evidence that air quality is or will become “Unhealthy for Sensitive Groups” or worse (e.g., during wildfire smoke or blowing dust events).
    • Advisories are issued for specific pollutants (e.g., ozone, fine particulate matter) or for specific types of air pollution events (e.g., blowing dust, wildfire smoke).
    • While daily AQI reports/forecasts are currently limited to areas with air quality monitors, air quality advisories may be issued anywhere in the state.
    • Similar to AQI reports/forecasts, advisories include information about possible health effects.
    • Advisories may include pollution prevention messages when appropriate.

EnviroFlash is a notification system sponsored by the U.S. EPA that sends out email messages about the air quality forecasts issued by state or local agencies such as CDPHE. The defined forecasts areas mentioned above are part of the EnviroFlash notification system.

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