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

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.

To quantify the associations of ambient temperature, fine particulate matter (PM_2.5), nitrogen dioxide (NO₂), and ozone (O₃) with PE onset in China.

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. PM_2.5, NO₂, and O₃ concentrations were obtained using high-resolution satellite-based models. Conditional logistic regression models were used to evaluate the associations of PM_2.5, NO₂, and O₃ concentrations with the onset of PE.

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). PM_2.5 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.

Ambient low temperature, NO₂, and PM_2.5 significantly increase the risk of PE onset. China's air quality improvements reduced the health risks of PM_2.5 but not those of NO₂. PE prevention should prioritize targeted NO₂ emission control alongside climate-adapted measures.