Ambient air pollution, low-grade inflammation, and lung function: Evidences from the UK Biobank

The associations of ambient air pollution exposure and low-grade inflammation with lung function remain uncertain. In this study, 276,289 subjects were enrolled in the UK Biobank. Individual exposure to ambient air pollution (including nitrogen dioxide [NO₂], nitrogen oxides [NO_x]), and particulate matter [PM_2.5, PM_10, PM_coarse]) were estimated by using the land-use regression model. Forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV₁) were tested, and low-grade inflammation score (INFLA score) was calculated for each subject. In this cross-sectional study, the median concentrations of air pollution were 9.89 µg/m³ for PM_2.5, 15.98 µg/m³ for PM₁₀, 6.09 µg/m³ for PM_coarse, 25.60 µg/m³ for NO₂, and 41.46 µg/m³ for NO_x, respectively. We observed that PM_2.5, PM₁₀, PM_coarse, NO₂, NO_x was negatively associated with lung function. Besides, significant positive associations between PM exposure and low-grade inflammation were noted. Per interquartile range (IQR) increase in PM_2.5, PM₁₀, and PM_coarse was related to higher INFLA score, and the β (95 % CI) was 0.06 (0.03, 0.08), 0.03 (0.02, 0.05), and 0.03 (0.01, 0.04), respectively. Additionally, we found significant negative associations between INFLA scores and lung function. One-unit increase in INFLA score was linked with 12.41- and 11.31-ml decreases in FVC and FEV₁, respectively. Compared with individuals with low air pollution exposure and low INFLA scores, participants with high air pollution and high INFLA scores had the lowest FVC and FEV₁. Additionally, we observed that INFLA scores could modify the relationships of PM_2.5, NO_2, and NO_x with FVC and FEV₁ (P_interaction <0.05). The negative impact of air pollutants on lung function was more pronounced in subjects with high INFLA scores in comparison to those with low INFLA scores. In conclusion, we demonstrated negative associations between ambient air pollution and lung function, and the observed associations were strengthened and modified by low-grade inflammation.