Associations of improved air quality with lung function growth from childhood to adulthood: the BAMSE study

Abstract

Background: The beneficial effect of improving air quality on lung function development remains understudied. We assessed associations of changes in ambient air pollution levels with lung function growth from childhood until young adulthood in a Swedish cohort study.

Methods: In the prospective birth cohort BAMSE (Children, Allergy, Environment, Stockholm, Epidemiology (in Swedish)), spirometry was conducted at the 8-year (2002-2004), 16-year (2011-2013) and 24-year (2016-2019) follow-ups. Participants with spirometry data at 8 years and at least one other measurement in subsequent follow-ups were included (1509 participants with 3837 spirometry measurements). Ambient air pollution levels (particulate matter with diameter ≤2.5 μm (PM_2.5), particulate matter with diameter ≤10 μm (PM₁₀), black carbon (BC) and nitrogen oxides (NO _x )) at residential addresses were estimated using dispersion modelling. Linear mixed effect models were used to estimate associations between air pollution exposure change and lung function development.

Results: Overall, air pollution levels decreased progressively during the study period. For example, the median (interquartile range (IQR)) level of PM_2.5 decreased from 8.24 (0.92) μg·m^-3 during 2002-2004 to 5.21 (0.67) μg·m^-3 during 2016-2019. At the individual level, for each IQR reduction of PM_2.5 the lung function growth rate increased by 4.63 (95% CI 1.64-7.61) mL per year (p<0.001) for forced expiratory volume in 1 s and 9.38 (95% CI 4.76-14.00) mL per year (p<0.001) for forced vital capacity. Similar associations were also observed for reductions of BC and NO _x . Associations persisted after adjustment for potential confounders and were not modified by asthma, allergic sensitisation, overweight, early-life air pollution exposure or dietary antioxidant intake.

Conclusions: Long-term reduction of air pollution is associated with positive lung function development from childhood to young adulthood.

FIGURE 1

Sex-specific associations between improvement of air quality and differences in forced expiratory volume in 1 s (FEV₁) and forced vital capacity (FVC) growth from age 8 to 24 years. Results were adjusted for age, height, body mass index (BMI) at age 8 years, municipality at birth, parental education level at birth, parental occupation at birth, maternal smoking during pregnancy, environmental tobacco smoke at 8 years, air pollution exposure during the first year of life, BMI at 16 and 24 years, active smoking at 16 and 24 years, and education level at 24 years. Estimates were interpreted as the difference in 1-year growth (95% CI) in FEV₁ and FVC for per unit improvement of air pollution concentrations, with positive values indicating positive associations between improved air quality and increased rate of FEV₁ or FVC growth. GLI: Global Lung Initiative; PM_2.5: particulate matter with diameter ≤2.5 μm; PM₁₀: particulate matter with diameter ≤10 μm; BC: black carbon; NO_x: nitrogen oxides.