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Arizona Department of Environmental Quality Arizona's Official Website
Office of Border Environmental Protection: Air
Office of Border Environmental Protection Air Quality

Brief History

The Coarse Particulate Matter (PM10) non-attainment status of the three largest Arizona cities along the international border - Nogales, Douglas and Yuma-San Luis - prompted ADEQ to expand its air quality monitoring efforts to Sonoran border cities in the mid-1990s.

In late 1993, ADEQ began monitoring (PM10) on both sides of the border in the cities of Nogales, Arizona and Nogales, Sonora (jointly known as Ambos Nogales.) A comprehensive study was completed in 1999 which included the following components: air sampling of particulate matter (PM), volatile organic compounds, semi-volatile organic compounds, and aldehydes; air emissions inventory; air modeling and human health risk assessment.

Upon completion of this project, ADEQ conducted a similar study in the cities of Douglas, Arizona and Agua Prieta, Sonora. This project included air sampling and the development of an air emissions inventory for both cities. A number of positive actions were taken in Agua Prieta while the study was under way including extensive road paving, completion of a modern landfill and tree plantings. The city had a noticeable improvement in air quality for three consecutive years, which prompted ADEQ to not proceed with the modeling and human health risk assessment phases of the study.

Finally, a third comprehensive binational study was undertaken in the Yuma, Arizona-San Luis Rio Colorado, Sonora area in the early 2000s. That project known as the Western Arizona-Sonora Border Air Quality Study (WASBAQS), is considered the largest binational air quality study ever along the United States-Mexico border. Air quality monitoring and emission inventories have been completed for this study.

In the summer of 2011, ADEQ discontinued its cross-border air quality monitoring program in San Luis Rio Colorado, Agua Prieta and Nogales, Sonora due to funding constraints. At the end of 2011, the Sonoran Commission on Ecology and Sustainable Development (CEDES) implemented a statewide air quality monitoring program, which included stations in Agua Prieta and Nogales, Sonora, and committed to sharing the data with ADEQ to help fill the data gap left by the discontinuation of ADEQ’s monitoring efforts in those two cities.

Arizona-Sonora Border Air Monitoring Stations

ADEQ conducts ambient air quality monitoring throughout Arizona. Environmental parameters measured in this monitoring network include criteria pollutants (O3, SO2, PM10, PM2.5, CO, and Pb), air toxics, and meteorology. For more information, please visit:

Currently, ADEQ has air quality monitoring stations in each of the three largest Arizona border cities - Douglas, Yuma and Nogales. An additional PM monitoring station is located at the Paul Spur lime plant in Cochise County. Over the next year, continuous PM10 and PM2.5 monitors will be installed at the Nogales and Douglas monitoring stations.

Border Region State Implementation Plans (SIPs)

When an area within the state violates federal Clean Air standards, ADEQ develops State Implementation Plans (SIPs) to identify the sources of pollution in an area and air pollution strategies that will help to bring the area back into compliance.

Outreach Efforts

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