Fine Particulate Matter and Polycyclic Aromatic Hydrocarbon Concentration Patterns in Roxbury, Massachusetts: A Community-Based GIS Analysis

Environmental Health Perspectives, April, 2001 by Jonathan I. Levy, E. Andres Houseman, John D. Spengler, Penn Loh, Louise Ryan

Given an elevated prevalence of respiratory disease and density of pollution sources, residents of Roxbury, Massachusetts, have been interested in better understanding their exposures to air pollution. To determine whether local transportation sources contribute significantly to exposures, we conducted a community-based pilot investigation to measure concentrations of fine particulate matter (particulate matter [is less than] 2.5 [micro]m; [PM.sub.2.5]) and particle-bound polycyclic aromatic hydrocarbons (PAHs) in Roxbury in the summer of 1999. Community members carried portable monitors on the streets in a 1-mile radius around a large bus terminal to create a geographic information system (GIS) map of concentrations and gathered data on site characteristics that could predict ambient concentrations. Both [PM.sub.2.5] and PAH concentrations were greater during morning rush hours and on weekdays. In linear mixed-effects regressions controlling for temporal autocorrelation, PAH concentrations were significantly higher with closer proximity to the bus terminal (p [is less than] 0.05), and both pollutants were elevated, but not statistically significantly so, on bus routes. Regressions on a subset of measurements for which detailed site characteristics were gathered showed higher concentrations of both pollutants on roads reported to have heavy bus traffic. Although a more comprehensive monitoring protocol would be needed to develop robust predictive functions for air pollution, our study demonstrates that pollution patterns in an urban area can be characterized with limited monitoring equipment and that university-community partnerships can yield relevant exposure information. Key words:, community-based research, fine particulate matter, geographic information system, personal exposure, polycyclic aromatic hydrocarbons, transportation. Environ Health Perspect 109:341-347 (2001). [Online 8 March 2001]

http://ehpnet1.niehs.nih.gov/docs/2001/109p341-347levy/abstract.html

As in many urban areas, residents in the Dudley Square area of Roxbury, Massachusetts (a neighborhood in Boston) have become increasingly concerned about respiratory health in their community. The prevalence of asthma in the United States has risen substantially over the past 20 years in all regions of the country (1), with rates within inner-city communities generally higher than rates elsewhere (2-6).

These general patterns have been found within the Boston area. A recent analysis (7) found that asthma hospitalization rates were far greater in Roxbury (9.8 hospitalizations per 1,000 people) than in Boston or in Massachusetts as a whole (4.2 and 2.1, respectively). In a cross-sectional analysis of Boston families, asthma prevalence was higher for families of lower socioeconomic status, with children 7.6 times more likely to have asthma [95% confidence interval (CI), 2.4-23.5] if they lived in zip codes with 20% of the population below the poverty level than in zip codes with less than 10% of the population below the poverty level (8). Although the areas of residence were not identified in the study, all zip codes in Roxbury fall within the higher poverty category. In addition, a small-scale survey by youth interns with the Roxbury Environmental Empowerment Project (REEP) found an asthma prevalence of 24% in Dudley Square (9).

Although the development and exacerbation of respiratory disease are multifactorial and complex, there is evidence of links between traffic and adverse respiratory outcomes. In recent studies, lung function (10,11), respiratory symptoms (10,12), medical care visits for asthma (13), and hospital admissions for asthma (14) were all associated with high traffic flow and proximity to main roads. Although these studies could not attribute respiratory symptoms to specific pollutants, other standard epidemiologic analyses have linked particulate matter and other transportation-related pollutants to a variety of health outcomes (15-17). Other research has shown that pollen particles can bind with diesel exhaust to ease their passage into the deep pockets of the lungs (18,19) and that pollen and other allergens are prominently found in road dust (20). Particle-bound polycyclic aromatic hydrocarbons (PAHs), a constituent of diesel exhaust, have been evaluated as potential carcinogens and mutagens (21,22) and have been shown to influence the immune system, potentially precipitating development of disease (23).

For residents of Dudley Square, the aforementioned survey by local schoolchildren found that traffic was perceived as the primary source of air pollution in the community (9). This is unsurprising, given the traffic density in the neighborhood and the visibility of the pollution sources. Dudley Square once housed an elevated train station, but this station was converted to a major bus terminal and transportation hub when the train was rerouted and the elevated tracks were removed in the 1980s. A recent survey by Alternatives for Community and Environment (ACE) found that 15 bus and truck depots are located within a 1.5-mile radius of Dudley Square, garaging more than 1,150 diesel vehicles, including approximately one-half of the Massachusetts Bay Transportation Authority bus fleet (24).