Air Quality Issues in the Four-state Border 2012 Region

The Four-state Region (FSR), as defined by the binational Border 2012 Environmental Program, includes those portions of the Mexican states of Tamaulipas, Nuevo León, and Coahuila within 100 kilometers (km) of the international border and the counties of Texas that fall within 100 km of the Texas' border with those three states. No areas in this region have violated any of the national standards for regulated pollutants in either country. Nevertheless, selected air quality concerns exist, most of them related to short-term local episodes but one related to a longer-term problem. These are caused either by meteorological conditions combined with the long-range transport of pollutants from outside the region, or by sporadic local air pollution events. The population and vehicle fleet (important with respect to gen- erating emissions) in the region are growing at high rates. The pop- ulation grew 36% from 1990 to 2000 in the Mexican portion of the FSR and 42% in the Texas portion. The combined population in 2000 was 2.74 million and could reach 3.79 million and 5.27 million