The effects of exposure to the environment around the World Trade Center after the attack of September 11, 2001, are not fully described. We evaluated 240 police first-responders; respiratory symptoms occurred in 77.5% but resolved or improved in around three fourths of subjects by the time of their evaluation (mean 69 days after the attack). Cough was the most common symptom (62.5%). Spirometric abnormalities were mild and occurred in 28.8%. Independent risk factors for abnormal spirometry were previous pulmonary disease or symptoms (adjusted odds ratio, 2.76) and intensity of exposure (AOR, 2.32). Previous pulmonary conditions were associated with obstructive defects (P<0.002). Exposure intensity was associated with a lower forced vital capacity (P<0.03) and a higher prevalence of abnormal spirometry (P<0.03). Officers with dyspnea, chest discomfort, or wheeze were more likely to have abnormal spirometry (P=0.04). A significant minority of officers had symptoms a few months after the exposure. Long-term effects of this respiratory tract exposure will need additional evaluation.