Air pollution has been associated with impaired health, including reduced lung function in adults. Moving to cleaner areas has been shown to attenuate adverse effects of air pollution on lung function in children but not in adults.

We conducted a prospective study of 9651 adults (18 to 60 years of age) randomly selected from population registries in 1990 and assessed in 1991, with 8047 participants reassessed in 2002. There was complete information on lung volumes and flows (e.g., forced vital capacity [FVC], forced expiratory volume in 1 second [FEV₁], FEV₁ as a percentage of FVC, and forced expiratory flow between 25 and 75% of the FVC [FEF_25–75]), smoking habits, and spatially resolved concentrations of particulate matter that was less than 10 μm in aerodynamic diameter (PM₁₀) from a validated dispersion model assigned to residential addresses for 4742 participants at both the 1991 and the 2002 assessments and in the intervening years.

Overall exposure to individual home outdoor PM₁₀ declined over the 11-year follow-up period (median, −5.3 μg per cubic meter; interquartile range, −7.5 to −4.2). In mixed-model regression analyses, with adjustment for confounders, PM₁₀ concentrations at baseline, and clustering within areas, there were significant negative associations between the decrease in PM₁₀ and the rate of decline in FEV₁ (P=0.045), FEV₁ as a percentage of FVC (P=0.02), and FEF_25–75 (P=0.001). The net effect of a decline of 10 μg of PM₁₀ per cubic meter over an 11-year period was to reduce the annual rate of decline in FEV₁ by 9% and of FEF_25–75 by 16%. Cumulative exposure in the interval between the two examinations showed similar associations.

Decreasing exposure to airborne particulates appears to attenuate the decline in lung function related to exposure to PM₁₀. The effects are greater in tests reflecting small-airway function.