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  • Air Monitoring

       Current Air Quality Information

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        The ultimate goal of the Pima County Department of Environmental Quality (PDEQ) air quality control program is to reduce the concentration of harmful air contaminants in ambient air to safe and healthy levels, and maintain those levels. A key process in controlling air pollution is to define the nature and extent of air quality problems through monitoring. Ambient air monitoring in the Tucson, Arizona area has been conducted by the PDEQ and its predecessors since the 1960's.

        PDEQ monitors for six criteria pollutants in the Tucson and Green Valley area in accordance to the regulations established by the Environmental Protection Agency (EPA).  This data is reported hourly here and to the EPA's Air Now website and is provided to various other agencies. An Air Index Now report that is based on the Air Quality Index (AQI) is generated hourly for public notification of current air quality conditions and how it may affect them. Below are the current values.

        If you cannot see the Air Index Now in the box below, the internet browser you are using may need to be updated.

                                           Carbon Monoxide (CO)   Ozone (O3)   Particulate Matter (PM)
        Besides the tabs below the Information, Education, Public Outreach and the Clean Air Program area will have additional information about air quality. As part of its role in the community, PDEQ offers educational, regulatory and professional group tours of its air quality monitoring facilities. Our highly trained staff can explain various aspects of air quality monitoring.  Many schools, including the University of Arizona, utilize these tours in their curriculum. Please call our Community Outreach Contact, at (520) 724-7400 if you would like more information on this service.

        Air Quality Index

        The Air Quality Index is the uniform procedure by which daily air pollution levels are reported to the public. AQI levels are set by the Environmental Protection Agency in accordance with section 319 of the Federal Clean Air Act.

        Air quality information is collected by the Pima County Department of Environmental Quality monitors located throughout Eastern Pima County. The monitors collect concentration information in parts per million and parts per billion for gases and micrograms per cubic meter for particulates. The level of pollution in the air and the related health effects are relayed to the public using the Air Quality Index. If a pollutant such as ozone has an AQI value of 59, the corresponding qualitative descriptor would be MODERATE. The AQI value of 100 generally corresponds to the National Ambient Air Quality Standard for the pollutant. AQI values below 100 are considered satisfactory while numbers above 100 are considered to be unhealthy.

        The AQI is the highest value for the pollutant in a 24-hour period. The highest 8-hour average for ozone and CO, and the highest 24-hour average for PM10 and PM2.5 . This report is used for daily statistics and historical summaries.

        The Air Index Now is used for the hourly updates of what the public is breathing at that moment.  This index is calculated using modifications to the AQI to give the most accurate estimate of what is in the air at that particular point in time. The report is also provided by Email to health professionals, local media and the public. To request reports by email contact the Community Outreach Contact at 724-7400.

        Air Pollution Data

        Current and Historic Air Pollution Data

        Please note: Many of these reports display values for 1-hour PM10 and PM2.5 (particulate matter 10 and 2.5 microns or less in diameter) concentrations. These data values are provided for informational purposes only. The EPA Health Standard for PM10 and PM2.5 is a 24-hour standard, based on the average of 24 hourly readings from midnight to midnight. The EPA has not yet developed a 1-hour standard for PM10 or PM2.5. 

        Historic 24-Hour Particulate Data:

          2000 2001 2002 2003 2004 2005 2006 2007
        PM2.5 csv  csv  csv  csv csv  csv  csv  csv
         PM10  csv  csv  csv  csv  csv  csv  csv  csv


          2008 2009 2010 2011 2012 2013 2014 
        PM2.5  csv  csv  csv  csv  csv  csv  csv
        PM10  csv  csv  csv  csv  csv  csv csv 

        Quality Assurance of Air Pollution Data

        Local agencies such as PDEQ involved in federal monitoring programs must comply with federal air quality assurance requirements. Each agency must develop and implement a Quality Assurance (QA) program consisting of policies, procedures, specifications, standards, and documentation necessary to:

        1. Provide data of adequate quality to meet monitoring objectives, and
        2. Minimize loss of air quality data due to malfunctions or out-of-control conditions.

        It is the policy of PDEQ to conduct and support appropriate quality assurance activities to ensure that these objectives are met.

        Monitoring Information

        Pima County Department of Environmental Quality monitors ambient (outdoor) air pollutants throughout eastern Pima County, including the Tucson metropolitan area and Green Valley. There are six principal pollutants, called “criteria” pollutants that are monitored in accordance with the National Ambient Air Quality Standards (NAAQS) set by the Environmental Protection Agency (EPA) to comply with the Federal Clean Air Act. The NAAQS were established to protect public health and the environment from harmful levels of air pollution.

        There are six air pollutants monitored by PDEQ which are: carbon monoxide (CO), ozone (O3), particulate matter (PM10 and PM2.5), nitrogen dioxide (NO2), sulfur dioxide (SO2) and lead (Pb).

        Map of monitoring locations and information about each site.  Click on the circles to get the site information.

        In addition, PDEQ is conducting a special Beryllium Monitoring Study to determine levels of beryllium in the air surrounding the Materion Ceramics (formally Brush Ceramics) facility in Tucson.

        The air quality monitoring section is divided into 3 units; the Field Monitoring unit, the Data Management unit and the Quality Assurance (QA) unit. The field monitoring unit conducts all quality control procedures related to routine operations such as calibrations, equipment checks, troubleshooting and repair of equipment necessary for air quality monitoring. The data management unit handles all operations related to network operations, data acquisition, management, storing and reporting of data. The QA unit operates independently of the field monitoring unit to assure the quality and accuracy of the data recovered.

        site exterior

        Almost all routine air quality monitoring data generated by PDEQ are submitted to the U.S. Environmental Protection Agency (EPA) AQS database system. Most air quality monitoring stations in the PDEQ network are equipped with electronic data loggers designed specifically for the logging of air quality data.

        The data loggers are programmed to take the electrical outputs from air quality monitoring instruments at a monitoring station and transmit this information via a modem to a central computer data acquisition system (DAS) located in the PDEQ offices. This information is then validated to detect possible erroneous readings, and stored in a central database. The information is then reported to the EPA, documented in summary reports, and made available to local agencies, researchers and the public. 


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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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