Ambient air pollution and hospitalisation for epilepsy in China: A nationwide, individual-level case-crossover study

Emerging evidence has indicated the detrimental effects of air pollutants on the central nervous system (CNS). However, few studies have examined the impact of air pollution on epilepsy morbidity at a nationwide scale in China. To address this gap, we conducted an individual-level, nationwide case-crossover study to investigate the association between air pollutants and epilepsy-related hospitalisations. Daily air pollution concentrations were estimated using high-resolution (1 km) satellite-based exposure models, and hospitalisation data were collected from 153 hospitals across 20 provinces in China between 2005 and 2020. Analysing data from 14,747 patients, we observed increased risks of epilepsy hospitalisations associated with exposure to nitrogen dioxide (NO₂) and ozone (O₃), with significant increases of 4.5 % (95 % confidence interval [CI]: 0.9 %, 8.4 %) and 4.9 % (95 % CI: 0.8 %, 9.3 %) per interquartile range (IQR) increment in lag 0 day exposure, respectively. The exposure-response curve for NO₂ was approximately linear at low concentrations but plateaued above 30 μg/m³. For O₃, the curve was flat at lower levels and steeper at higher concentrations. Female patients and children were more susceptible to NO₂ exposure, with 10.5 % and 9.1 % increases in hospitalisations per IQR increment, respectively. O₃-related risks were more pronounced among patients in northern regions and during the warm season. This individual-level, nationwide case-crossover study provides the first evidence that short-term exposure to NO₂ and O₃ elevates the risk of epilepsy-related hospitalisations. These findings underscore the need for stricter air quality standard to mitigate the detrimental effects of air pollution on CNS diseases.