Symptoms, lung function, and airway responsiveness following irritant inhalation.

STUDY OBJECTIVE To estimate the incidence of respiratory symptoms and physiologic abnormalities after inhalation of common irritant chemicals. DESIGN Structured interview of 12 months of poison control center (PCC) inhalation cases. Follow-up measurement of pulmonary function and airway responsiveness in a subgroup with symptoms 12 to 24 h postexposure. SETTING A regional PCC and clinical pulmonary function laboratory. PATIENTS Consecutive sample of 547 inhalation cases. Interviews of 299 subjects. Lung function follow-up in 10 subjects. MEASUREMENTS AND MAIN RESULTS Immediate respiratory symptoms were reported by 262 (88 percent) subjects; 12 to 24 h postexposure symptoms were reported by 130 (44 percent). Cigarette smoking was significantly related to immediate onset of cough (relative risk [RR] = 1.3; 95 percent confidence interval [CI], 1.1 to 1.5); both smoking (RR = 1.6; 95 percent CI, 1.1 to 2.1) and prior asthma (RR = 1.3; 95 percent CI, 1.1 to 1.6) were associated with wheeze, exhibiting multiplicative combined risk (RR = 2.8; 95 percent CI, 1.9 to 4.3). Of 10 subjects studied, none had abnormal airflow or lung volumes 8 +/- 4 days postexposure; 8 demonstrated increased airway responsiveness to methacholine. By three months, only one subject's increased responsiveness reversed; in three others, symptoms resolved but increased responsiveness remained. CONCLUSIONS Respiratory symptoms following irritant exposure are associated with smoking and asthma and typically resolve quickly. Continuing symptoms are associated with persistent increased airway responsiveness without other pulmonary function abnormalities. This may reflect newly induced airway changes or, alternatively, could represent underlying increased responsiveness in subjects symptomatic after irritant exposure.