The effects of environmental tobacco smoke exposure on lung function in a longitudinal study of British adults

Small effects of environmental tobacco smoke exposure on lung function have been demonstrated in many studies of children, but fewer studies have exam ined adults in this respect. We examined these relations in a 7-year longit udinal study of 1,623 British adults, age 18-73 years, who were nonsmokers throughout. Outcome was measured by forced expiratory volume in 1 second (F EV1) adjusted for sex, age, and height. Exposure was assessed by asking sub jects whether they lived with a smoker (at both the initial and the follow- up studies) and by salivary cotinine measurements (follow-up study only). C ross-sectionally, subjects exposed at home showed tiny FEV1 deficits at bot h studies of -4 ml [95% confidence limits (CL) = -31, 23] and -5 ml (95% CL = -32, 22), respectively. Cotinine adjusted for potential confounders show ed a stronger association with FEV1, with the highest quintile showing a -1 05-ml deficit (95% CL = -174, -37) in comparison with the lowest. Longitudi nally, no clear relation was apparent between change in FEV1 and average ex posure or change in exposure. These results indicate that environmental tob acco smoke is associated with small deficits in adult lung function, consis tent with our meta-analysis estimate of a 2.7% deficit in exposed nonsmokin g adults. The relations seen with cotinine but not with household exposure may reflect the importance of exposure outside the home.