Air pollution, Spirometry, Elderly

Background: Air pollution exposure has been associated with both reduced lung function and increased cardio-pulmonary mortality (CPM). We analyzed the relationship between air pollution, reduced lung function and CPM. Methods: We used data from the German SALIA cohort including 2527 elderly women (aged 55 years at baseline 1985-1994) with a 22-year follow-up to CPM. Exposures to PM10, PM2.5, PM2.5 absorbance, NO2 and NOx were assessed by land-use regression modeling and back-extrapolated to estimate exposures at baseline. Lung function (FVC, FEV1) was measured by spirometry and transformed to GLI z-scores. Adjusted Cox proportional hazards and causal mediation analysis models were fitted. Results: The survival analysis showed that reduced lung function (GLI z-scores of FVC or FEV1 below 5% predicted) reflected significantly lower survival probability of CPM (p < 0.0001). Exposures to NOx and NO2 were associated with an increased risk of CPM (HR=1.228; 95%CI: 1.029 – 1.466 for an IQR increase in NOx and HR=1.233; 95%CI: 1.033 – 1.471 for NO2) after adjusting for potential covariates, the exposure of PM10 and PM2.5 was not significant. The mediation analysis showed the significant indirect effect of all pollutants exposure on CPM mediated by reduced FEV1 and FVC, while the strongest effect was found for PM10 and PM2.5.The mediated proportion of FEV1 in the associations between PM10, PM2.5, PM2.5 absorbance, NOx and NO2 on CPM was 18.5% (p=0.014), 17.2% (p=0.048), 13.8% (p=0.014), 7.4% (p=0.020) and 9.4 (p=0.002). 10/06/2020 2/2 Conclusions: Long-term exposure to air pollution is associated with CPM. Furthermore, exposure to air pollution associated with CPM was significantly mediated by lung function.