Abstract
People with cancer may be susceptible to acute environmental stressors, including ambient fine particulate matter (PM2.5), but the contribution of traffic-related particles to short-term cancer mortality remains uncertain. We analysed daily cancer mortality records by cancer site from 2000 to 2019 across eight countries (Australia, Brazil, Canada, Chile, South Korea, Mexico, New Zealand and Thailand). A time-stratified case-crossover design was used to assess associations with all-source PM2.5 and traffic-sourced PM2.5 (TSPM2.5). The analysis included 9,223,612 cancer deaths. Every 10 μg m−3 increase in the 2-day moving average of all-source PM2.5 exposure (lag 0–1) was associated with a 0.77% increase in all-cancer mortality risk (95% confidence interval (CI) 0.64–0.89%). The corresponding increase in TSPM2.5 was associated with a 3.87% increase (95% CI 3.28–4.47%). Although TSPM2.5 represented only 14.72% of total PM2.5 concentrations, it accounted for 73.55% of PM2.5-attributable cancer deaths during the study period, equivalent to 1.21% (95% CI 1.03–1.39%) of total cancer mortality. Effect modification by age, sex or socioeconomic status was not statistically significant. Reducing TSPM2.5 exposure may help lower acute pollution-related mortality risks among people with cancer.