Characterization of ambient particulate matter in El Paso del Norte region

Air pollution in the Paso del Norte region, where West Texas abuts the southern boundary of New Mexico and the northern boundary of Chihuahua, Mexico is a common concern to the residents on both sides of the border. Parts of region fail to meet he U.S. and Mexican Ambient Air Quality Standards for particulate matter, ozone, and carbon monoxide. The regional air pollution problem is complicated due to arid climate, complex terrain topography, frequently occurring temperature inversions, extensive unpaved urban areas, an aging and poorly maintained vehicle fleet, and number of other uncontrolled anthropogenic emission sources. The issue is further complicated by concerns arising from recent scientific evidence of health effects associated with exposures to fine particulate matter. A study designed to address particulate matter (PM) air pollution problems in the region is currently undertaken by researches from member universities of the Southwest Center for Environmental Research and Policy and several governmental agencies. The study attempts to 1) characterize the fine fraction of PM; 2) identify and characterize the major regional emission sources; 3) apportion the fine fraction of PM to the source emissions; and 4) establish a regional technological information clearinghouse. The short-term goal of this research is to initiate a research program to characterize, identify, and quantify the sources and nature of the PM in the region. The long-term goal of this study is to establish regional research capabilities to continue air quality monitoring, evaluation, modeling and control after implementation of the study. A scoping study to collect regional PM was conducted in December 1998. Several 2-hour and 24-hr samples were collected on medium-vol samplers, low-vol dichotomous samplers, single-filter Federal Reference Method PM10 or PM25 samplers for chemical speciation and high resolution microscopy. A full-scale study will be performed later to further characterize ambient PM concentrations based on the observations from the scoping study. Emissions profiles for the major sources will be collected, and the full-scale study will include deep characterization of selected samples using inductively coupled plasma mass spectrometry for overall elemental composition, confocal microscopy for interstitial particle characterization, and X-ray near edge adsorption spectroscopy for metal speciation. Source apportionment receptor modeling will also be performed. This paper discusses the objectives and plan outlined in the study along with some preliminary results and remarks from the scoping study