Short-term exposure to air pollution and acute health effects in a low-pollution region, Baden-Wurttemberg, Germany

Background The acute effects of short-term air pollution exposure on human health in regions with low pollution concentrations is not widely explored. This study assesses the risk of mortality and morbidity linked to short-term exposure to NO 2 and PM 2.5 in Baden-Wurttemberg, Germany, a region that broadly complies with European air quality standards and global guidelines. Methods We applied a two-stage time-stratified case-crossover design followed by meta-analyses to estimate the relative risks of mortality (all-cause), hospital admission and sick leave (all-cause and cause-specific). Health outcomes between 2013 and 2022 were collected from the regional public insurance records, and exposures were derived from ensemble air quality models. Effect modification by SARS‑CoV‑2 (COVID-19) years, age, sex and urbanisation were also evaluated. Results Short-term exposure to PM 2.5 and NO 2 was associated with increased risks of several acute health outcomes. Associations were observed for all-cause and cardiovascular-related hospital admissions, as well as sick leave, even at concentrations near the current daily limits set by the European Union. Effect estimates were generally more pronounced for NO 2 and concentrated at immediate lag days. Exposure–response relationships were non-linear across health outcomes, and little evidence of effect modification by demographic or urbanisation characteristics was observed. Conclusion This study provides evidence of acute health risks from short-term exposure to PM 2.5 and NO 2 , even at concentrations below the suggested daily permissible levels, emphasising the need to reassess existing air quality standards.