A fter the September 11, 2001, terrorist attack on the World Trade Center (WTC), rescue workers from the Fire Department City of New York (FDNY) experienced substantial and immediate reductions in pulmonary function, 1 particularly in FEV 1 . FDNY fi refi ghters had an average adjusted FEV 1 decline of 355 mL in the fi rst 6 months after September 11, 2001, which is . 10 times the average annual agerelated decline of 27 to 30 mL. 2,3 Declines were persistent, resulting in little or no average recovery during the subsequent 6 years. 3 During the same time, FDNY rescue workers reported increased upper-respiratory symptoms, lower-respiratory symptoms (LRSs), and gastroesophageal refl ux symptoms, 4 with an exposureresponse gradient based on earliest arrival time 5 and work duration. 4,6 Modest associations between decreased pulmonary function and increased respiratory symptoms have been described in the general adult population 7,8 and in elderly persons 9 ; after occupational, dust, or pollutant