Environmental health issues along the United States-Mexico border: an airshed in evolution.

The El Paso area represents a unique ecosystem with a transboundary airshed shared by 3 cities, 3 states, and 2 countries. That toxic air pollutants respect no borders is exemplified clearly in this federally designated nonattainment area. However, a combination of grassroots involvement and studies under way through the scientific community has led to evolving approaches directed at improving air quality and identifying its impact on human health. The involvement of physicians and cooperative efforts among governments and communities has and will be key in this continued effort.