Effect of ozone on bronchial reactivity in atopic and nonatopic subjects.

We studied the effect of exposure to ozone (0.6 ppm, 2 h) on bronchial reactivity in 16 otherwise healthy, nonsmoking subjects with normal pulmonary function. On the basis of medical history and allergen skin testing, 7 subjects were classified as nonatopic; 9, as atopic. Bronchial reactivity was assessed by measuring the increase in specific airway resistance (SRaw) produced by inhaling histamine or methacholine aerosol before and after sham exposure and after ozone exposure. Nonatopic subjects inhaled 10 breaths of histamine (16 mg/ml solution) and of methacholine (10 mg/ml solution); atopic subjects inhaled 10 breaths of histamine (8 mg/ml solution). In neither group of subjects was the response to histamine affected by sham exposure (p > 0.5). In the nonatopic subjects, the increase in SRaw produced by histamine (6.57 ± 1.43 cm H2O/L/s · L, mean ± SEM) and by methacholine (8.94 ± 2.12 cm H2O/L/s · L) after ozone exposure were significantly greater than after sham exposure (3.42 ± 0.64 and 3.62 ± 0.61 ...