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.
