Ambient temperature, air pollutants, and pulmonary embolism onset: a 17-year nationwide study in China

Background The short-term effects of the interaction between ambient temperature and air pollution on the onset of pulmonary embolism (PE) remain a critical public health concern. Evidence from large-scale, multicenter studies is limited. Objectives To quantify the associations of ambient temperature, fine particulate matter (PM2.5), nitrogen dioxide (NO2), and ozone (O3) with PE onset in China. Methods We conducted a nationwide time-stratified case-crossover analysis of 48 589 PE cases from hospital-based registries across China (2005-2021). Meteorological data were obtained from fixed-site monitoring stations. PM2.5, NO2, and O3 concentrations were obtained using high-resolution satellite-based models. Conditional logistic regression models were used to evaluate the associations of PM2.5, NO2, and O3 concentrations with the onset of PE. Results Ambient low temperature significantly increased the risk of PE onset, with an odds ratio (OR) of 1.47 (95% CI, 1.19-1.80) at an extremely low temperature (−11.6 °C) compared with the reference (23.4 °C). At lag day 0, each 10 μg/m3 increase in NO2 was significantly associated with PE onset (OR, 1.011; 95% CI, 1.003-1.018). PM2.5 showed a weaker effect (OR, 1.004), while O3 showed no significant association. Significant pollutant effects were observed exclusively during the warm season. NO2 remained significantly associated with PE onset despite overall improvements in air quality after 2014. Conclusion Ambient low temperature, NO2, and PM2.5 significantly increase the risk of PE onset. China's air quality improvements reduced the health risks of PM2.5 but not those of NO2. PE prevention should prioritize targeted NO2 emission control alongside climate-adapted measures. © 2026 International Society on Thrombosis and Haemostasis.