Most of the New York City firefighters and medics whose lungs were damaged by pulverized masonry and glass from the World Trade Center attacks 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 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 attacks, according to 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 is in Thursday's New England Journal of Medicine.
The study dims hopes that workers who developed respiratory problems after being exposed to the trade center's powdery and smoking 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.
In the immediate aftermath, 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.
Overall, firefighters in the study experienced, in one event, the normal loss of lung function caused by aging 12 years, Prezant said.
The research was based on tests that measure how fast a person can exhale.
The fire department routinely 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 on the exams.
Not every person who scores below normal on a test suffers noticeable breathing problems. A person sitting at a desk might not feel anything amiss, Prezant said. Others may feel more winded than usual while playing sports or chasing their child around the backyard.
"But for firefighters," he said, "it can be a big difference. They have to run up six flights of stairs carrying 50 to 100 pounds of equipment."
Additionally, about 2 percent of firefighters and 7.5 percent of EMTs in the study tested poorly enough to have symptoms similar or worse to asthma sufferers.
People normally lose some lung capacity each year as they age, and the study accounted for that decline.
Researchers don't know what is causing the loss of lung function to persist, Prezant said. He said the problems may 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 also shows that the firefighters who lost lung function generally aren't getting worse over time, aside from the 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.
The study, like previous ones, has shown that the people who suffered the worst damage were those who were caught in the dust plume when the towers collapsed.
Prezant himself was briefly buried in the debris on 9/11, and spent several minutes gagging and choking on air so thick with particles he described it as "syrupy charcoal paste."
He and two other study authors are also involved in evaluating applications by fire department members to retire on a disability pension.