Soot particles spewing from the exhaust of diesel trucks constitute a major contributor to the alarmingly high rates of asthma symptoms among school-aged children in the South Bronx, according to the results of a five-year study by researchers at New York University's School of Medicine and Robert F. Wagner Graduate School of Public Service.
Over the course of the study, asthma symptoms, particularly wheezing, doubled among elementary school children on high traffic days, as large numbers attend schools in close proximity to busy truck routes because of past land-use decisions.
The South Bronx has among the highest incidences of asthma hospital admissions in New York City, and a recent city survey of asthma in the South Bronx's Hunts Point district found an asthma prevalence rate in elementary school of 21 percent to 23 percent. The South Bronx is surrounded by several major highways, including Interstates 95, 87, 278 and 895. At Hunts Point Market alone, some 12,000 trucks roll in and out daily.
The study is a collaboration of NYU School of Medicine, the Robert F. Wagner Graduate School of Public Service, and four community groups - The Point Community Development Corporation, Sports Foundation, Inc., We Stay/Nos Quedamos, Inc., and Youth Ministries for Peace & Justice Inc. Endorsed by Congressman Jose E. Serrano, the aim of the study was to examine the impact of industrial emissions on air quality and to direct policy initiatives. Serrano sponsored the press conference today where the findings were discussed.
As part of the investigation, the NYU team dispatched a mobile van lab to assess ground-level pollution levels, and they conducted a "Backpack Study" to monitor carbon concentrations taken from air samples collected by commuting students. The findings have shown that high concentrations of air pollution worsen asthma problems among elementary school children in the South Bronx.
The schools in the study were: PS 154, MS 302, CS 152 and MS 201. Ten elementary school children with asthma from each of the four schools were followed for a month. Data on respiratory symptoms, lung function, activity patterns, as well as personal air pollution exposures were collected at the same time.
According to the study, among all of the children the daily average exposure to tiny particulate matter smaller than 2.5 microns (PM2.5) ranged from 20 to 50 micrograms per cubic meter. In addition, the Environmental Protection Agency's proposed daily limit of 35 micrograms per cubic meter was exceeded on about one-third of the study days. Only about 10 percent of the total mass of tiny particles was diesel soot, but it was this portion that was most closely related to children's adverse health effects.
Particles smaller than 2.5 microns (a human hair is 100 microns thick) have been mostly closely linked to lung and heart disease. The EPA has regulated PM2.5 since 1997, limiting each person's average exposure per year to no more than 15 micrograms per cubic meter.
Other studies have shown that people who live near highways have a higher incidence of asthma. But researchers had not measured levels of traffic air pollutants that individuals were being exposed to. "We went in and actually measured personal exposures to traffic pollution, which had not been done before. Our results confirm that diesel soot particles in air pollution are causing exacerbations of asthma in children," says George Thurston, Sc.D., Associate Professor of Environmental Medicine at NYU School of Medicine, one of the study's principal researchers.
The major type of air pollutant that was associated with symptoms of asthma was elemental carbon. This type of carbon, called black soot, is found in diesel exhaust and is a component of particulate matter in pollution that is smaller than 2.5 microns. This type of carbon has been cited as a causal agent in asthma in a number of other controlled-exposure studies in the laboratory.
Past land use decisions have placed school children in close proximity to highways, truck routes, industrial land-use areas and other environmental hazards. Modeled concentrations of traffic-related particulate matter and nitrogen oxides are two to five times higher in close proximity South Bronx highways than in other parts of the South Bronx. About one-fifth of all pre-K to 8th-grade students in the South Bronx attend schools within less than two blocks of major highways.
"If you live in the South Bronx, your child is twice as likely to attend a school near a highway as other children in the city," according to Rae Zimmerman, professor of planning and public administration at the Robert F. Wagner Graduate School of Public Service, a principal researcher for the study.