Most of the New York City firefighters and medics whose lungs were damaged by pulverized masonry and glass from the Sept. 11 attack on the World Trade Center are not improving as time goes by, according to a new study.

The results are based on breathing tests from nearly 11,000 firefighters who were at ground zero in the first two weeks when the dust cloud was thickest. Of the firefighters who didn't smoke, 13 percent were still scoring below normal up to seven years later, the study found.

That number was down from 18 percent who initially tested below normal after the attack, said researchers at the New York City Fire Department and the Albert Einstein College of Medicine.

Among emergency medical technicians, the numbers were worse. Of the nearly 2,000 EMTs included in the analysis, 22 percent of the nonsmokers scored below normal on their most recent breathing test.

The research, in today's New England Journal of Medicine, dims hopes that workers who developed respiratory problems after being exposed to the trade center's remnants would gradually return to normal.

Firefighters commonly suffer some lung damage after being exposed to heavy smoke, but the problem is not usually long-term. Previous studies of firefighters who lost breathing capacity after battling chemical and forest fires found that they generally recovered within days or weeks.

That hasn't happened with 9/11 responders, said Dr. David Prezant, the Fire Department's chief medical officer and a lead author of the study. He and other researchers noted that the particle cloud released by the trade center collapse was unique.

They were exposed to "unprecedented density of dust, smoke, all kinds of materials that they don't encounter in a routine course of firefighting," said Dr. Thomas Aldrich, professor of medicine at Albert Einstein.

Firefighters studied experienced, in one event, the loss of lung function caused by aging 12 years, Prezant said. The study accounted for the loss of lung capacity each year a person ages.

The research was based on tests that measure how fast a person can exhale.

The fire department gives its members the tests periodically. Before 9/11, only 3 percent of nonsmoking firefighters and 11 percent of nonsmoking EMS workers scored below normal.

Additionally, about 2 percent of firefighters and 7.5 percent of EMTs in the study tested poorly enough to have symptoms similar to or worse than asthma sufferers.

Researchers don't know what is causing the loss of lung function to persist, Prezant said. He said the problems might be due to chronic inflammation, originally caused by particles or chemical exposure, that is causing the airways to remain partially obstructed.

Dr. Philip Landrigan, who oversees the World Trade Center Medical Monitoring and Treatment Program at Mount Sinai Hospital, said the study does contain a positive note: It shows that firefighters who lost lung function generally aren't getting worse, aside from normal decline due to aging.

"After the initial loss, which was sharp and dramatic, it has stabilized, and that reflects the fact that these people are getting good medical care," said Landrigan, who had no role in the study.

Source: Associated Press