Persistent Hyperreactivity and Reactive Airway Dysfunction in Firefighters at the World Trade Center

Abstract

New York City Fire Department rescue workers experienced massive exposure to airborne particulates at the World Trade Center site. Aims of this longitudinal study were to (1) determine if bronchial hyperreactivity was present, persistent, and independently associated with exposure intensity, (2) identify objective measures shortly after the collapse that would predict persistent hyperreactivity and a diagnosis of reactive airways dysfunction 6 months post-collapse. A representative sample of 179 rescue workers stratified by exposure intensity (high, moderate, and control) without current smoking or prior respiratory disease was enrolled. Highly exposed workers arrived within 2 hours of collapse, moderately exposed workers arrived later on Days 1-2; control subjects were not exposed. Hyperreactivity at 1, 3, and 6 months post-collapse was associated with exposure intensity, independent of ex-smoking and airflow obstruction. Six months post-collapse, highly exposed workers were 6.8 times more likely than moderately exposed workers and control subjects to be hyperreactive (95% confidence interval, 1.8-25.2; p = 0.004), and hyperreactivity persisted in 55% of those hyperreactive at 1 and/or 3 months. In highly exposed subjects, hyperreactivity 1 or 3 months post-collapse was the sole predictor for reactive airways dysfunction (p = 0.021). In conclusion, development and persistence of hyperreactivity and reactive airways dysfunction were strongly and independently associated with exposure intensity. Hyperreactivity shortly post-collapse predicted reactive airways dysfunction at 6 months in highly exposed workers; this has important implications for disaster management.

Lessons From the World Trade Center Disaster

“…[6][7][8][9][10] Studies postulated primary airway rather than parenchymal disease based on normal chest radiographs and either bronchial hyperreactivity and/or airway wall thickening and AT on CT scan examination. 7,10,12,13,29 The fall in VC in fi refi ghters from before to after September 11, 2001, correlated with degree of AT assessed by plethysmography, 12 and reduced VC and TLC was associated with AT on CT scan in other fi rst responders. 11 The present study extends these observations by demonstrating normal static lung mechanics, normal maximal Pel, and absence of parenchymal disease on high-resolution CT scan.…”

“…22 Resistance and reactance were calculated from airfl ow and pressure oscillations between frequencies of 5 to 35 Hz. Parameters included the following: (1) resistance at oscillation frequencies of 20 Hz (R 20 ) and 5 Hz (R 5 ), (2) fre quency dependence of resistance calculated as change in resistance between 5 and 20 Hz (R [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] ), (3) resonant frequency (Fres), and (4) reactance area (AX). Trials with stable tidal and end-expiratory volume were analyzed.…”

“…Airway disease was demonstrated by bronchial hyperreactivity or presence of bronchial wall thickening and/or air trapping (AT) on CT scan. 7,[10][11][12][13] This population of subjects exposed to WTC dust with unexplained reduction in VC provided the opportunity to assess airway and parenchymal mechanics in addition to spirometry and plethysmography. The present study (1) characterizes a physiologic phenotype of restrictive dysfunction due to airway injury and (2) contrasts the restrictive dysfunction from airway disease to the physiologic phenotype of patients with interstitial lung disease (ILD).…”

Asthma in Medicaid Managed Care Enrollees Residing in New York City: Results from a Post-World Trade Center Disaster Survey

“…Research conducted among firefighters found that exposure to dust and smoke was associated with bronchial hyperreactivity, bronchial responsiveness, and the onset of cough. 10,11 A post 9/11 survey of adults living south of 110th found that 27% of respondents reported an increase in asthma severity. 12 This study reinforces the finding that respiratory symptoms associated with the collapse of the WTC buildings were not limited to individuals directly involved with the rescue and cleanup activities.…”

Pulmonary Function after Exposure to the World Trade Center Collapse in the New York City Fire Department

“…Appropriate respiratory protection was initially not readily available; later, compliance was suboptimal (3). WTC exposure has since been implicated in "WTC cough," and upper and lower airway inflammation with airway obstruction and bronchial hyperreactivity (4)(5)(6)(7)(8)(9)(10)(11)(12).…”