Obstructive airways disease with air trapping among firefighters exposed to world trade center dust

Background: The World Trade Center (WTC) collapse produced a massive exposure to respirable particulates in New York City Fire Department (FDNY) rescue workers. This group had spirometry examinations pre-September 11, 2001, and post-September 11, 2001, demonstrating declines in lung function with parallel declines in FEV₁ and FVC. To date, the underlying pathophysiologic cause for this has been open to question. Methods: Of 13,234 participants in the FDNY-WTC Monitoring Program, 1,720 (13%) were referred for pulmonary subspecialty evaluation at a single institution. Evaluation included 919 full pulmonary function tests, 1,219 methacholine challenge tests, and 982 high-resolution chest CT scans. Results: At pulmonary evaluation (median 34 months post-September 11, 2001), median values were FEV₁ 93% predicted (interquartile range [IQR], 83%-101%), FVC 98% predicted (IQR, 89%-106%), and FEV 1 /FVC 0.78 (IQR, 0.72-0.82). The residual volume (RV) was 123% predicted (IQR, 106%-147%) with nearly all participants having normal total lung capacity, functional residual capacity, and diffusing capacity of carbon monoxide. Also, 1,051/1,720 (59%) had obstructive airways disease based on at least one of the following: FEV₁ /FVC, bronchodilator responsiveness, hyperreactivity, or elevated RV. After adjusting for age, gender, race, height and weight, and tobacco use, the decline in FEV₁ post-September 11, 2001, was significantly correlated with increased RV percent predicted ( P < .0001), increased bronchodilator responsiveness ( P < .0001), and increased hyperreactivity ( P = .0056). CT scans demonstrated bronchial wall thickening that was significantly associated with the decline in FEV₁ post-September 11, 2001 ( P = .024), increases in hyperreactivity ( P < .0001), and increases in RV ( P < .0001). Few had evidence for interstitial disease. Conclusions: Airways obstruction was the predominant physiologic finding underlying the reduction in lung function post-September 11, 2001, in FDNY WTC rescue workers presenting for pulmonary evaluation.