Low-level ambient air pollution exposure and risk of lung cancer – a pooled analysis of 7 European cohorts

Abstract

PDS 68: Outdoor air pollution, mortality and morbidity, Exhibition Hall (PDS), Ground floor, August 26, 2019, 10:30 AM - 12:00 PM Background/Aim: Ambient air pollution has been associated with lung cancer but the shape of the exposure-response function - especially at lower exposure levels - is not well described. The aim of this study was to address the relationship between long-term low-level air pollution exposure and lung cancer incidence. Methods: The “Effects of low level air pollution: A study in Europe” (ELAPSE) collaboration pools 7 cohorts from across Europe. We developed hybrid models combining monitoring and land use data, satellite observations, and dispersion model estimates for nitrogen dioxide (NO2), fine particulate matter (PM2.5), black carbon (BC), and ozone (O3) to assign exposure to participants’ residential addresses. We analyzed the pooled data by stratified Cox proportional hazards models adjusting for potential confounders. We developed linear and natural cubic spline models, analyses based on subsets and thresholds across the exposure distribution, and multi-pollutant models to disentangle potential inter-dependencies between pollutants. Results: A total of 307,550 persons were included in the analyses. During a mean follow-up of 18.1 years, 3,956 incident lung cancer cases occurred. Median (5–95%) exposure levels of NO2, PM2.5, BC and O3 (warm season) were 24.2 µg/m3 (12.8–39.5), 15.4 µg/m3 (8.7–19.4), 1.6 10-5/m (0.7–2.1), and 86.6 µg/m3 (70.4–92.9), respectively. We observed a higher risk for lung cancer with higher exposure to PM2.5 (HR 1.13, 95% 1.05-1.23 per 5 µg/m3) after adjustment for covariates. The association was similar across subsets of exposure-levels with no sign of a threshold below which no association was evident. The effect estimate was also robust to the inclusion of co-occurring pollutants. We did not find significantly positive associations between NO2, BC or O3 and lung cancer incidence. Conclusions: Our results indicate that long-term ambient PM2.5 exposure may contribute to lung cancer incidence even at concentrations lower than current EU limit values and WHO Air Quality Guidelines.