Exploring the Impact of Air Pollution Sources on Incident Lung Cancer in a Northern Swedish Cohort

Abstract

Abstract Background Exposure to particulate air pollution seem to be a contributing cause to lung cancer incidence; however, the role of the size and composition of the particles is still unclear. The objective was to assess the association between source-specific concentrations of ambient particulate air pollution and lung cancer incidence in a Swedish cohort in a low-level area. Methods Participants in the Västerbotten intervention programme cohort from Northern Sweden were recruited between January 1990 and December 2014 and followed until diagnosis for lung cancer, as defined by Swedish national hospital, cause of death and pharmaceutical registers. Exposure to total particulate matter with aerodynamic diameter ≤ 10 µm (PM10) and ≤ 2.5 µm (PM2.5) as well as source-specific PM concentrations from traffic (PM10-traffic), exhaust (PM2.5-exhaust) and wood burning (PM2.5-wood burning) was estimated at each individual’s home address using dispersion models with high spatial resolution (down to 35 x 35 m2). For the years of follow-up, the moving average of source-specific pollutants was calculated for the time windows 1–5 years (lag 1–5) and 6–10 years (lag 6–10) preceding the outcome. Cox regression models were used to assess Hazard Ratios (HRs) and 95% Confidence Intervals (CIs) for the association between air pollution exposure and lung cancer incidence, adjusted for relevant potential confounding factors. Results The median age of the 51,064 participants was 40 years at baseline. During 421,466 person-years of follow-up, 253 incident cases of lung cancer were observed. Non-statistically significant risk increases associated with PM10, PM2.5, PM10-traffic, PM2.5-exhaust and PM10-wood burning, respectively in single-pollutant unadjusted models. The risk estimates changed considerably by adjustment for individual-level baseline covariates as well as area-level socioeconomics. The HR for incident lung cancer associated with a 1 µg/m3 increase in PM2.5-exhaust was 1.20 (95% Confidence Interval, CI: 0.65–2.23), whereas the corresponding HR associated with PM2.5-wood burning was 1.05 (95% CI: 0.70–1.57), in single-pollutant models. Conclusions There was some evidence for an association between exposure to particles from traffic, but not wood burning, and incidence of lung-cancer in this register-based study, but not for with particles from wood burning.