Diesel Truck Soot Linked to Asthma

NEW YORK, New York, October 17, 2006 (ENS) - Fine particulate matter from the exhaust of diesel trucks is a major contributor to the high rates of asthma in children in the South Bronx, according to a five-year study released Monday by New York University. The study found that 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.

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," said George Thurston, an associate professor of Environmental Medicine at NYU School of Medicine and one of the study's principal researchers. "Our results confirm that diesel soot particles in air pollution are causing exacerbations of asthma in children."

The South Bronx has among the highest asthma rates in New York City, with recent studies indicating more than 20 percent of elementary school children suffer from the respiratory ailment.

For this latest investigation, the research team dispatched a mobile van lab to assess ground-level pollution levels. In addition, they gave 40 elementary students special backpacks to collect further data on air quality. asthma

More than six million American children suffer from asthma. (Photo courtesy Boston Public Schools)
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 fine particulate matter, known as PM2.5, ranged from 20 to 50 micrograms per cubic meter.

The researchers report that the U.S. Environmental Protection Agency's (EPA) daily PM2.5 limit of 35 micrograms per cubic meter was exceeded on about one-third of the study days.

Although only about 10 percent of the total mass of tiny particles was diesel soot, it was this portion that was most closely related to children's adverse health effects, the researchers said.

They found 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.

"Essentially this study is a call to further action," said Representative Jose Serrano, a Democrat representing South Bronx. "We cannot sit idly by and let our children suffer because of past land use and transportation planning decisions, which are now causing so much harm in the South Bronx."

The area is surrounded by several major highways - at the South Bronx Hunts Point Market alone, some 12,000 trucks roll in and out daily.


The study specifically identified soot from diesel trucks as the primary pollutant of concern.(Photo courtesy EPA)

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.

The study comes in the wake of considerable controversy over the EPA's new standards for particulate matter. Last month EPA Administrator Stephen Johnson announced a tightening of the daily PM2.5 standard from 65 micrograms per cubic meter to 35 micrograms, but opted not to change the annual standard of 15 micrograms.

The latter decision drew widespread outrage from public health experts, who contend there is ample evidence that the standard should be between 12 and 14 micograms. EPA's Clean Air Science Advisory Committee, in an unprecedented move, sent Johnson a letter expressing dismay that the new standards do not reflect their recommendations.