Prezant also didn't have to recruit for study subjects from the general public, which might have skewed the results.
"Our study is not influenced by selecting the most ill or least ill," said Prezant.
Overall, the study showed the proportion of firefighters with below-normal lung function went from 3 percent before the attacks to 18 percent after. Eight years later that number stabilized at 13 percent.
"We take these answers and immediately translate them into monitoring and treatment initiatives," Prezant said.
Doctors, politicians and lawyers have all looked to previous studies as a call, not only for better treatment, but better prevention too.
"The 9/11 terrorist attack resulted in an unprecedented environmental disaster. The urgency of the search and rescue efforts led to first responders not being diligent in protecting themselves from the dust cloud by wearing properly fitted respiratory protection, such as disposable NIOSH N95 masks," said Dr. James Sublett of the American College of Allergy, Asthma and Immunology.
"An emphasis on worker protection would have likely ameliorated the type of permanent lung damage demonstrated in this follow-up of the firemen and EMS workers," he said.
Lung specialists who reviewed the study said the damage to the rescue workers at Sept. 11 exceeds the usual smoke damage from fires.
"The decrease is much greater than that observed with historical smoke and dust exposure and appeared to permanently reduce lung function," said Dr. Mark Gladwin, chief of Pulmonary, Allergy and Critical Care Medicine at the University of Pittsburgh Medical Center. "There was an expectation that this would improve in the overall cohort, but this did not happen."
However, doctors pointed out that the study did have a silver lining. Although the firefighters and EMTs did not recover during the study period, they didn't get worse after the first year.
"While recovery does not appear to have occurred to any significant degree, the good news is that after the original damage to lung function the rate of lung function loss returned to the normal range," said Dr. Neil Schachter, the medical director at the Respiratory Care Department at Mount Sinai Hospital in New York City.
"The event had not caused an accelerating loss of lung function, as has been the case with some exposures," he said.