“This exposure at ground zero was so unique that no one could have predicted the impact on lung function. We demonstrated dramatic decline in lung function, mostly in the first 6 months after 9/11, and these declines persisted with little or no meaningful recovery of lung function among FDNY rescue workers (firefighters and emergency medical service workers) over the next 6 and a half years,” said David Prezant, M.D., professor of medicine at Einstein and senior author of the study.
In this 7-year study, the evaluated workers included nearly 92 percent of the 13,954 FDNY firefighters and EMS workers present at the WTC site between Sept. 11 and Sept. 24, 2001. Lung function in these 12,781 individuals was assessed by spirometry testing performed every 12 to 18 months. Spirometry measures the amount of air exhaled in a single breath.
“Severe and Persistent” Decline
All participants had been tested pre-9/11, so those spirometric results provided a baseline for assessing lung-function decline. Because the decline was severe and persistent, a substantial proportion of FDNY rescue workers were left with abnormal lung function by the end of this study – Sept.11, 2008. For example, the proportion of those who never smoked – and whose lung function was below normal – increased over the first year from 3 percent to 18 percent for firefighters and from 12 percent to 22 percent for EMS workers, stabilizing at about 13 percent for firefighters and 22 percent for EMS workers by the end of the seven-year study.
“Previous studies have indicated that the effects of firefighting on lung function are mild and reversible,” said lead author Thomas Aldrich, M.D., professor of medicine at Einstein and an attending physician in the pulmonary medicine division at Montefiore. “The difference seems to be that the workers in our study population experienced repeated daily exposures to much higher concentrations of airborne particulates (solid particles suspended in the air) and gaseous chemicals.”
Aldrich suggests that the lack of long-term recovery among the 9/11 rescue workers may be due to several factors: the unusual nature of the dust cloud itself, which was thick with particulates; inhaled pulverized material from the collapse of the towers; and smoke from fires that continued to burn until mid-December.
“All smoke contains particulates, but not at the density seen in the WTC collapse, especially if you were at the site during the first two or three days or for long durations thereafter,” said Aldrich. “In a normal fire, you don’t get enveloped in a particulate cloud so thick that you can’t even see through it.”
The paper, “Lung Function in Rescue Workers at the World Trade Center after 7 Years,” appears in the April 7 online edition and April 8 print edition of The New England Journal of Medicine. The study was funded by the National Institute of Occupational Safety and Health.