U.S. EPA and the San Diego County Air Pollution Control District were scheduled to unveil a new air pollution monitor Tuesday at the San Ysidro port of entry, located on the US-Mexico border about 16 miles from downtown San Diego. Fifty thousand cars and buses and 25,000 pedestrians cross there daily, making it the busiest land port of entry in the Western Hemisphere.

The monitor measures PM 2.5 (fine particulate matter up to 2.5 microns in diameter), which can result in negative health effects when inhaled. The device, which begins operating today, will be used to collect real time data on the levels of air pollutants in San Ysidro and adjoining communities. EPA is providing $110,000 to the SDAPCD for the two year project that includes the purchase, installation, and operation of the monitor. At the conclusion of the study, if PM 2.5 levels are elevated, the District and EPA will identify its sources and work to reduce it where possible.

“Air pollution knows no boundaries,” said Jared Blumenfeld, EPA’s Regional Administrator for the Pacific Southwest. “The goal is to protect our communities near the border through a better understanding of the soot that may be affecting San Ysidro, whether from tailpipe emissions or wood smoke.”

In collaboration with the U.S. General Services Administration (GSA) and the U.S. Customs and Border Protection, the monitor has been placed on the roof of the pedestrian building at the port of entry. Data from the monitor are posted on the SDAPCD website and will be used to help address air pollution challenges in nearby communities. At the completion of the monitoring period, the EPA and SDAPCD will analyze the data and determine next steps. The closest PM 2.5 monitor is in Chula Vista, Calif., about 6 miles north of the port of entry, and does not provide data representative of PM 2.5 emissions at the Border.

“This air pollution monitor will allow us to track San Ysidro’s air quality and craft solutions to improve the air that local residents breathe,” said County Supervisor Greg Cox, who represents the area.

Binational environmental pollution is addressed through the Border 2020 Environment Program – a bi-national collaborative effort with a mission to protect human health and the environment along the U.S.–Mexico border. To date, EPA has invested over $600 million in border environmental projects.  For more about EPA’s Border 2020 Program, please visit: www.epa.gov/border2020

PM 2.5 is one of the most pressing challenges to clean air today. When inhaled, this complex mixture of extremely small particles can reach the deepest regions of the lungs. Health studies have shown a significant association between exposure to fine particles and premature death from heart or lung disease.

Air pollution presents a substantial environmental risk in some border communities that are frequently exposed to elevated concentrations of particulate matter PM10 and PM2.5, ozone, and toxic air pollutants. Communities that deal with multiple environmental stressors are often disadvantaged and more vulnerable to the impacts of air pollution. The border region includes a number of cities that share common airsheds; thus, activities in one city can directly affect the other, whether in the same country or across the border.