Lung Function Trajectories in World Trade Center-Exposed New York City Firefighters Over 13 Years: The Roles of Smoking and Smoking Cessation

Abstract

Background: World Trade Center (WTC)-exposed Fire Department of the City of New York firefighters lost, on average, 10% of lung function after September 11, 2011, and >10% developed new obstructive airways disease. There was little recovery (on average) over the first 6 years. Follow-up into the next decade allowed us to determine the longer-term exposure effects and the roles of cigarette smoking and cessation on lung function trajectories.

Methods: We examined serial measurements of FEV1 from March 11, 2000, to September 10, 2014, among 10,641 WTC-exposed Fire Department of the City of New York firefighters with known smoking and body weight histories.

Results: The median number of FEV1 measurements during follow-up was 9; 15% of firefighters arrived at the WTC during the morning of September 11, 2001; and 65% never smoked. Firefighters arriving the morning of September 11, 2001 averaged lower lung function than did lesser exposed firefighters; this difference remained significant during most of follow-up (P < .05). Never smokers had significantly better lung function than current smokers; former smokers fell in between, depending upon their cessation date. Those arriving the morning of September 11, 2001 were more likely to have an FEV1 < lower limits of normal compared with those arriving between September 13, 2001, and September 24, 2001 (OR = 1.70, P < .01). Current smokers were more likely to have an FEV1 < lower limits of normal compared with never smokers (OR = 2.06, P < .01), former smokers who quit before September 11, 2001 (OR = 1.96, P < .01), or those who quit between September 11, 2001 and March 10, 2008 (OR = 1.49, P < .01).

Conclusions: Thirteen years after September 11, 2001, most firefighters continued to show a lack of lung function recovery, with the trajectory of decline differing by WTC exposure and smoking status. Unlike the immutable effect of WTC exposure, we demonstrated the benefit on lung function of smoking cessation in this unique occupational/environmental cohort.

Keywords: World Trade Center; firefighting; occupational lung disease; pulmonary function test; smoking.

Figure 1

Flow chart for firefighter study participation. WTC = World Trade Center.

Figure 2

Lung function by WTC arrival time. For both graphs, the population was restricted to never smokers as of the end of the study. (A) Actual FEV₁ adjusted by age on September 11, 2001 (centered at 40 years), height (centered at 179 cm), weight (centered at 200 lb), sex (men as reference), and race (whites as reference). (B) Percent predicted FEV₁ adjusted by age on September 11, 2001 (centered at 40 years), and weight (centered at 200 lb). See Figure 1 legend for expansion of abbreviation.

Figure 3

Lung function by smoking status smoking status was measured as of the end of the study. (A) Actual FEV₁ adjusted by age on September 11, 2001 (centered at 40 years), height (centered at 179 cm), weight (centered at 200 lb), sex (men as reference), and race (whites as reference). (B) Percent predicted FEV₁ adjusted by age on September 11, 2001 (centered at 40 years), and weight (centered at 200 lb).

Figure 4

Abnormal lung function by smoking status. The proportions of firefighters by smoking status, at each 1.5- to 2.5-year interval, who had an FEV₁ measurement less than the lower limit of normal (A) or less than 70% predicted (B).