Air Quality Advisories

Pima County Department of Environmental Quality monitors air quality at 14 different monitoring stations located throughout eastern Pima County.

Those of us who live here are very fortunate since Pima County has healthy air quality the most of the time. However, there are some days where air quality is less than ideal and we would like to let you know when those days occur.

Sign up now to receive Air Quality Advisories and other Pima County Department of Environmental Quality notices via email. Be one of the first to know when the Tucson/Eastern Pima County area is experiencing poor air quality. As an added benefit, you will also receive occasional notices of special PDEQ services and activities available in our community to improve air quality and the environment.

Enter your email address below to register for PDEQ’s email notifications. The list serve contacts will be kept confidential and only used by PDEQ. For more information, call (520) 724-7446 or e-mail Beth Gorman.

Particulate matter is a generic term used to describe a complex group of air pollutants that vary in size and composition, depending upon the location and time of its source.  The PM mixture of fine airborne solid particles and liquid droplets (aerosols) include components of nitrates, sulfates, elemental carbon, organic carbon compounds, acid aerosols, trace metals, and geological material.  Some aerosols are formed in the atmosphere from gaseous combustion by-products such as volatile organic compounds (VOCs), oxides of sulfur (SOx) and nitrogen oxides (NOx).  The size of PM can vary from coarse wind blown dust particles to fine particles directly emitted or formed from chemical reactions occurring in the atmosphere.  PM10 comprises particles with an aerodynamic diameter less than or equal to a nominal 10 microns.  PM2.5 comprises particles with an aerodynamic diameter less than or equal to a nominal 2.5 microns.

Ground level ozone forms near Earth's surface when the ultraviolet light in sunlight triggers a chemical reaction with "precursor pollutants" emitted by cars, power plants, and industrial sources.  These precursor pollutants consist of nitrogen oxides (NOx) and volatile organic hydrocarbons (VOC).  Ozone near ground level is a harmful pollutant.  Ozone levels are carefully monitored during the summer months when the weather conditions are perfect for it to form.  Sunshine, hot temperatures, and high emissions of NOx and VOC pollutants lead to high levels of ozone.