We attempted to determine the association between occupational and air
pollutant exposure with the development of adult asthma through the a
nalysis of a standardized respiratory questionnaire administered to a
cohort of 3914 nonsmoking adults in 1977 and again in 1987. Ambient ai
r pollution concentrations were estimated over a 20-year period using
monthly interpolations from fixed-site monitoring stations applied to
zip code locations by month of residence and work site. Second-hand sm
oke exposure was significantly associated with the development of asth
ma (related risk [RR] = 1.45, confidence interval [CI] = 1.21 to 1. 75
). Airways obstructive disease before age 16 was related to a marked i
ncreased risk (RR = 4.24, CI = 4.03 to 4.45). An increased risk of ast
hma was significantly associated with increased ambient concentrations
of ozone exposure in men (PR = 3.12, CI = 1.61 to 5.85).