Between 20 percent and 25 percent of the 1,720 rescue workers have developed "really significant asthma," Weiden said.
"Without provocation, their lung function is pretty good. When they're exposed to an irritant, their lung function declines. That's very bad for firefighters."
But why did they develop asthma? The study suggests that their lungs were injured by exposure to World Trade Center dust and became more sensitive. However, doctors didn't find unusual signs of lung scarring, Weiden said, which would suggest that something else occurred.
"Now that we have a clear understanding of what they've got, we can focus our attention on treating it," he said. "We can nail down for the rest of the community the observation that this is airway injury and we can treat it like asthma."
Dr. Jacqueline Moline, director of the World Trade Center Medical Monitoring and Treatment Program at Mount Sinai Medical Center in New York City, said the findings confirm previous research and reveal the persistence of lung problems related to the collapse of the twin towers.
The rescue workers "have persistent health effects and need to be followed and treated in the years to come," she said. "People are still ill, their health has been adversely affected and they should be provided with care."
New York City has details on the World Trade Center Registry, which monitors people exposed to the disaster.
SOURCES: Michael D. Weiden, M.D., medical officer, New York City Fire Department; Jacqueline Moline, M.D., director, World Trade Center Medical Monitoring and Treatment Program, Mount Sinai Medical Center, New York City, March 2010, Chest
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