El Paso county is situated in West Texas. The city of El Paso lies at the county’s southernmost tip. It is here that many of the county’s pollution problems originate. The city of El Paso shares a common border with Ciudad Juarez in Mexico. The two cities are divided by the Rio Grande river. As well as the shared border, they also share a water supply and air shed due to their enclosure in a valley between two mountain ranges.

El Paso shares an air shed with the Mexican city of Ciudad Juarez. This air shed, known as Paso del Norte, sits in a basin composed of the mountains that surround the two cities. Within the air shed, visibility is often poor and respiratory problems frequent. Paso del Norte’s air problems stem from a variety of emission sources combined with unfortunate meteorological conditions. El Paso fails to meet U.S. federal air quality standards and is therefore designated as a federal nonattainment area. It exceeds the levels deemed safe of ozone,carbon monoxide and PM-10. An index developed to rate cities according to weighted estimates of exposure to air pollutants ranked El Paso as the nation’s sixth worst.

Many toxic chemicals from industrial and agricultural sources find their way into the Rio Grande river. In 1995, there were more than 1,400 industrial plants in the border area. In the same year, 30 potentially-damaging chemicals were found in the river that exceeded screening levels. These included arsenic, cadmium, chromium, copper, lead, nickel, selenium, zinc and mercury. As of 2002, El Paso ranks in the worst 60 percent of cities in terms of its major chemical releases and their associated cancer risks, developmental toxicants and reproductive toxicants.

Lead is the most common land contaminant in El Paso, followed by copper. El Paso has two facilities responsible for releasing toxic chemicals into the land. These are the U.S. Army Air Defense Artillery Center and the Phelps Dodge Copper Products Company.