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BACKGROUND: The terrorist attacks on the World Trade Center (WTC) on September 11, 2001 exposed thousands of Fire Department of New York City (FDNY) rescue workers to dust, leading to substantial declines in pulmonary function (PF) in the first year. For most workers, these declines persisted, without recovery over at least the next 6 years, leaving a substantial proportion with abnormal lung function. However, a minority experienced some improvement, while others experienced further decline. The reasons for this heterogeneity have not been well explained.
METHODS: Male FDNY firefighters who arrived at the WTC site on or before 9/24/2001; who had PF tests prior to 9/11/2001, between 9/12/2001 and 9/11/2002, and at least one additional PF test after 9/11/2009; with weight loss <= 30 lbs. or weight gain <= 60 lbs. were eligible for this study. PF change was classified as “improved” (last forced expiratory volume in one second (FEV1) > first FEV1 after 9/11/2001), “expected decline” (0 to 780 ml difference between last FEV1 and first FEV1 [median difference was 390 ml]), or “substantial decline” (>780 ml difference). Contingency tables and logistic regression analyses were used to assess the association between PF group and WTC exposure intensity as measured by initial arrival time at the WTC site (high=morning of 9/11/2001, moderate=afternoon of 9/11/2001 or anytime 9/12/2001, low=9/13/2001-9/24/2001), smoking history (ever, former, never as of 9/11/2001 and change in smoking behavior during follow-up), age, height, weight, ethnicity, and magnitude of PF decline between the last PF test prior to 9/11/2001 and the first PF test after 9/11/2001.
RESULTS: Analyses included 5516 firefighters who met inclusion criteria and had complete covariate data; 731 (13.3%) experienced improved PF and 816 (14.8%) experienced substantial decline. In the multivariate analyses, weight gain over the follow-up period was associated with lower odds of improved PF (odds ratio [OR] 0.74, 95% confidence interval [CI] 0.70-0.79 for each ten pound weight increase) and greater odds of substantial decline (OR 1.28, 95% CI 1.21-1.36 for each ten pound weight increase). Age, height, smoking, and magnitude of PF decline between last PF prior to 9/11/2001 and first PF after 9/11/2001 were all associated with either improved PF or substantial decline. WTC exposure and ethnicity were not associated with either outcome.
CONCLUSIONS: Even modest weight gain was associated with lower odds of PF improvement and increased odds of substantial decline in PF in FDNY WTC-exposed firefighters even after controlling for smoking.