A new survey of Sept. 11-related illnesses has found a sharp increase in asthma â€” 12 times higher than normal â€” among those who worked on the toxic debris piles of ground zero, the Associated Press reports.
The study, released Monday by the New York City Department of Health, was based on responses gathered by the World Trade Center Health Registry.
The data show 3.6 percent of the 25,000 rescue and recovery workers in the registry reported developing asthma after working at the site â€” more than 12 times the expected figure for adults over a similar time period.
"The risk was significantly elevated for fire and rescue workers, medical workers, and police and military personnel compared to volunteers," according to the study published in the journalEnvironmental Health Perspectives.
Overall, workers who arrived at the disaster site on the day of the attacks and stayed more than 90 days reported the highest rate of new asthma â€” 7 percent. Volunteers accounted for almost one-third of those responding to the survey; firefighters accounted for about 14 percent.
Workers who reported wearing protective respirators on Sept. 11 and 12, when the contamination was at its worst, had lower risk of developing adult-onset asthma, the study found.
"These findings reflect the critical importance of getting appropriate respiratory protection to all workers as quickly as possible during a disaster, and making every effort to make sure workers wear them at all times," said Dr. Thomas Frieden, the city's health commissioner.
The results support previous research that found 70 percent of workers at ground zero later suffered lung problems. The doctors who conducted that study said they expect thousands to need treatment for 9/11 illnesses.
The authors of the new asthma study cautioned the findings are based on self-reporting by those answering their survey questions, so they cannot verify diagnoses or rule out over-reporting by those who responded.