NEW YORK -- In New York City, air pollution levels have typically been monitored by inanimate objects, at more than a dozen locations around town.
But in the South Bronx, from 2002 to 2005, air pollution monitors went mobile. They went to the playground, to the gritty sidewalks, even to the movies.
A group of schoolchildren carried the monitors everywhere they went. The instruments, attached to the backpacks of children with asthma, enabled researchers at New York University to measure the pollution the children were exposed to, morning to night.
The South Bronx is home to miles of expressways, more than a dozen waste-transfer stations, a sewage treatment plant and truck traffic from some of the busiest wholesale produce, meat and fish markets in the world.
It is also home to some of the highest asthma hospitalization rates for children in the city.
The New York University study found that the students were exposed to high levels of air pollutants in their neighborhoods and that children in the South Bronx were twice as likely to attend a school near a highway as were children in other parts of the city.
The findings paint a bleak picture of the air quality in one of the poorest sections of New York City and have focused renewed attention from community groups and elected officials on curbing pollution from truck exhaust.
"The levels did surprise me," said Jose E. Serrano, the congressman whose district includes the South Bronx and who helped secure federal money for the study. "They are really telling us that this is a very serious problem."
Serrano, a Democrat, and the researchers conducted a news conference this month about the findings. Ten children from each of four schools in the South Bronx took part in the study. They were given wheeled black and dark blue backpacks outfitted with a battery-powered pump and air filter, along with other instruments.
"You rolled it, so it wasn't really that heavy," said Derrick Reliford, one of the students.
The children, volunteers ages 10 to 12, each took part in the study for a month. They reported to researchers stationed at the schools twice a day and kept diaries on their asthma symptoms and daily activities. Their lung function was tested, and the filters from their backpacks were regularly changed and analyzed. A van parked outside the schools served as an air-monitoring laboratory.
Derrick, 14, took part in the study in 2002, when he was a student at Public School 154. The school is across the street from the Major Deegan Expressway.
Airborne particles like dust, soot and smoke that are less than 2.5 micrometers in diameter are small enough to lodge themselves deep into the lungs. Studies have linked pollution of this sort to respiratory problems, decreased lung function, nonfatal heart attacks and aggravated asthma, according to the U.S. Environmental Protection Agency.
EPA officials said these fine particles, a significant portion of which are produced by diesel engine emissions, lead to 15,000 premature deaths a year nationwide.
In 18 of the 69 days taken over the three-year period in the South Bronx study, average daily exposure to fine-particle pollution for a group of 10 children exceeded the EPA's standards, which will be set to 35 micrograms per cubic meter in December.
"I think it's an indicator that these kids are being exposed to very high fine-particle concentrations on a fairly regular basis," said George Thurston, associate professor of environmental medicine at the NYU School of Medicine and one of the study's principal researchers.
Walter Mugdan, director of environmental planning and protection for the EPA region that includes New York, said he had not seen the detailed study, which was financed in large part by an EPA grant.
He cautioned that there were differences between the methods used by the agency and by researchers to gather data on air pollution.
Four Bronx organizations that supported the study - including the Point, a Hunts Point community group - have asked pro bono lawyers to look into their legal options to get the EPA and the state to improve air quality in the South Bronx.
New York state must submit a plan to the EPA by April 2008 detailing how it will bring its fine-particle pollution levels into compliance. States that fail to submit or implement their plans risk losing federal highway money.
The State Department of Environmental Conservation said in a statement that the state plan is under development and will be released for public comment late next year.
Fine-particle pollution levels are expected to decrease as a result of city, state and federal measures already in place, the statement said.
Thurston said the findings of the study, which will be published in a scientific journal next year, showed that only 5 percent to 10 percent of the fine particle pollution was soot from diesel exhaust, but it was that portion that seemed to be having the worst effect on the children's asthma.
He said that their symptoms, like wheezing, doubled on days when pollution from truck traffic was highest.
The research was conducted by the Institute for Civil Infrastructure Systems at the university's Wagner Graduate School of Public Service.