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INTRA-URBAN GRADIENTS OF FINE PARTICULATE MATTER (PM2.5) IN THE EL PASO CHILDREN'S HEALTH STUDY
Citation:
Neas, L, S Rhoney, D Walsh, M Gonzales, J. W. Scott, AND R. P. Clickner. INTRA-URBAN GRADIENTS OF FINE PARTICULATE MATTER (PM2.5) IN THE EL PASO CHILDREN'S HEALTH STUDY. Presented at ISEA, Charleston, SC, November 4-8, 2001.
Description:
El Paso, Texas, a metropolitan area with over 500,000 residents, is located directly across the US/Mexico border from Ciudad Juarez with over 1 million residents. An estimated 18 million vehicles annually cross the international border between these two large cities. The border crossing congestion from these vehicles, as well as the normal intra-urban and interstate traffic, produces a considerable amount of mobile source emissions including fine particulate matter (PM2.5). Previous studies have shown associations between PM2.5 and adverse health effects in both children and adults. The El Paso area provides an opportunity to investigate further the human health effects from PM exposure.
The El Paso Children's Health Study was a large epidemiological study, in which questionnaires were distributed to all students enrolled in the fourth and fifth grades of the 53 elementary schools in the El Paso Independent School District (EPISD). Twenty of these schools, divided among the four EPISD regions, were selected for school-based air quality monitoring and for pulmonary function testing of those students with parental consent on a returned questionnaire. The pulmonary function testing was conducted over a six-week period from late March to early May 2001 with three to four schools scheduled each week. Concurrent with the pulmonary function testing at each school, 24-hour PM2.5 samples were collected using a portable compact sampler located on the school's roof. This sampling system consisted of a Sibata pump operating at 1.7 L/min attached to a URG sample train fitted with a laminar flow element, PEG coated impactors and Teflon coated filter screens supporting a pre-weighed 25mm PTFE filter to be used for gravimetric analysis.
To further assess the PM2.5 levels across the four EPISD regions, four Ruppert and Patashnick 2025-D automated sequential PM2.5 samplers, one in each region, were placed on the roofs of selected elementary schools. These samplers were located at four schools for three weeks and then moved to four different schools for another three weeks. This design provides PM2.5 data at each site for three weeks across eight different sites. Each sequential sampler utilizes a 50%/50% split flow to expose simultaneously two different filters. PM2.5 samples were collected on pre-weighed Teflon filters (for gravimetric and elemental analysis) and on pretreated quartz filters (for organic/elemental carbon analysis). The samplers were operated at a flow of 8.3 L/min for each type of filter and the samples were collected over 24-hour periods. The data presented will examine spatial gradients of 24-hour PM2.5 concentrations across a large metropolitan area using both compact samplers and sequential dichotomous samplers.
(This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.)