Extreme temperature, PM2.5, and mortality across 115 Chinese communities: a prospective PURE-China cohort study

Evidence on the combined effects of extreme temperature events and PM 2.5 exposure on mortality remains limited, particularly in populations outside high-income countries. We aimed to evaluate the associations of extreme heat and cold events with all-cause and cardiovascular mortality in China and their joint effects with PM 2.5 exposure. We analyzed data from 43,264 participants aged 35–70 years in the Prospective Urban Rural Epidemiology (PURE)-China cohort across 115 communities in 12 provinces. Daily temperature and PM 2.5 exposures during 2008–2021 were assigned at the community level using ERA5-Land and CHAP datasets. Heat and cold events were defined using community-specific percentile thresholds and duration criteria. Time-dependent Cox models were used to estimate associations across climate zones, and climate-specific estimates were pooled using random-effects meta-analysis. Heat- and cold-related analyses were restricted to warm and cold seasons, respectively. During a median follow-up of 11.9 years, heat events during the warm season were associated with increased risks of all-cause and cardiovascular mortality. The strongest association was observed for cardiovascular mortality during heat events lasting ≥ 3 days (95th percentile, P95_3d; HR: 2.51, 95% CI: 1.51 to 4.19). Cold events during the cold season were also associated with elevated mortality risk, with the strongest association for cardiovascular mortality during P5_3d events (HR: 1.78, 95% CI: 1.07 to 2.95). Higher PM 2.5 exposure amplified the associations of both heat and cold events with all-cause mortality, with joint HRs of 2.77 (95% CI: 1.78 to 4.33) and 3.84 (95% CI: 2.48 to 5.96), respectively. Sensitivity analyses yielded consistent results. Extreme heat and cold events were associated with increased all-cause and cardiovascular mortality in China. Higher PM 2.5 exposure further modified temperature-related mortality risks, supporting integrated climate adaptation and air quality strategies.