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  • Air Quality Forecasts and Action Days

    Pima County Department of Environmental Quality monitors air quality at 16 different monitoring stations located throughout eastern Pima County.

    Beginning January 1, 2023, PDEQ will move away from issuing High Pollution Advisories and Health Watches and instead implement a different type of air quality forecast called Air Quality Action Days.

    PDEQ and the Arizona Department of Environmental Quality (ADEQ) have historically issued High Pollution Advisories to warn the public when air pollutant concentrations have the potential to reach unhealthy levels. However, both agencies use different forecasting methods, which can create confusion for the public. To differentiate the two, PDEQ will begin using "Air Quality Action Days" when monitored concentrations for ground-level ozone (O3), dust (PM10), or smoke (PM2.5) are expected to reach or exceed 90 on the Air Quality Index (AQI). These symbols will now be used for the Air Quality Action Days: 
    Air Quality Action Days Icons

    Air quality forecasts are based on the Environmental Protection Agency (EPA) federal health standards for the six criteria pollutants (ground-level ozone, particulate matter, carbon monoxide, nitrogen dioxide, sulfur dioxide, and lead), displayed for the public in the AQI. PDEQ's Air Quality Action Days will only measure ground-level ozone and particulate matter, as these are the pollutants of most concern in Pima County.

    When PDEQ issues Air Quality Action Days, the alert will include information about the health effects that can result from the pollutant and list the populations most susceptible to exposure. It will also recommend how to avoid exposure and share information on how individuals can reduce their contribution to the particular air pollution emissions. 

    ADEQ will continue to issue High Pollution Advisories when there is a high probability for a pollutant to exceed the federal health standard and High Pollution Watches when there is the potential for a pollutant to exceed the federal health standard.

    Sign up now to receive Air Quality Action Day Alerts and other Pima County Department of Environmental Quality notices via email. 

    You can also sign up to receive ADEQ air quality forecasts. 

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    Department of Environmental Quality

    33 N. Stone Ave., Suite 700
    Tucson, AZ 85701

    Phone: (520) 724-7400
    Fax: (520) 838-7432

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