Association of ambient fine particulate matter with increased emergency ambulance dispatches for psychiatric emergencies: a time-series analysis

Abstract

BackgroundAs a top ambient pollutant in urban area, fine particulate matter (PM2·5) has been associated with the occurrence and deterioration of many medical conditions, while few studies have observed the association with psychiatric conditions. We aimed to investigate the association between short-term PM2·5 exposure and psychiatric emergency events, and further explored the variation by age, sex, and seasonal patterns, which have been suggested to be associated with both psychiatric risk and pollutant toxicity. MethodsWe used time-series analysis to investigate the association between short-time exposure (0–3 days) of PM2·5 and emergency ambulance dispatches for psychiatric emergencies in Beijing, one of the most polluted cities in China during the study period. We did stratified analyses to examine the effects of age, sex, and seasonal pattern. FindingsBetween 2008 and 2014, 158 634 psychiatric emergencies were recorded. Every 10 μg/m3 increase of the PM2·5 concentration was associated with a 0·12% increase of the same-day overall psychiatric emergencies (95% CI 0·03–0·22; p=0·013) and a 0·12% increase of the suicide-related psychiatric emergencies at lag 2 (2 days after PM2·5 exposure; 0·01–0·24; p=0·041). The associations remained when adjusted for sunlight duration. The age effect that children (<18 years) were more likely to be involved in suicide-related psychiatric emergencies after PM2·5 exposure than adults (18–64 years) was significant (percentage change for children vs adults of 0·84% vs 0·07% at lag 3; p=0·013). No significant association was found among the older population (≥65 years; p=0·050–0·825). However, sex and seasonal effects were not statistically significant on the PM2·5 and psychiatric emergencies association (p=0·052–0·999). InterpretationWe found a positive association between acute PM2·5 exposure and increased psychiatric emergency presentations as indicated by emergency ambulance dispatches data. Children were more vulnerable to acute PM2·5 elevation and developed psychiatric problems, especially suicide. We suggest that preventive attention for psychiatric emergencies should be paid after acute PM2·5 elevation, particularly to children. FundingNational Natural Science Foundation of China (81801344), China Postdoctoral Science Foundation (189826), Postdoctoral Fellowship of Peking-Tsinghua Center for Life Sciences, and the Swedish Research Council (2015-06372).