Ambient fine particulate matter is associated with increased emergency ambulance dispatches for psychiatric emergencies.

Aims: As a top ambient pollutant in urban area, fine particulate matter (PM) has been associated with the occurrence and deterioration of many medical conditions, while limited studies have observed the association with psychiatric conditions. This study aimed to investigate the association between short-term PM 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.

Methods: We used time-series analysis to investigate the association between short-term exposure of PM and emergency ambulance dispatches for psychiatric emergencies (EPE) (n = 158634) in Beijing, one of the top polluted cities in China during the study period between 2008 and 2014. Stratified analyses were conducted to examine the effects of age, sex and seasonal pattern.

Results: Every 10 μg/m increase of the PM concentration was associated with a 0.12% increase of the same-day overall EPE (95% CI: 0.03-0.22%, p = 0.013) and a 0.12% increase of the suicide-related EPE at lag 2 (95%CI: 0.01-0.24%, p = 0.041). The associations remained when adjusted for sunlight duration. An age effect was observed where children (age <18) showed a higher risk of suicide-related EPE after PM exposure compared to adults (18 ≤ age≤64). We did not observe evidence of effect modification by sex and season based on the results of stratified analysis.

Conclusions: We found a positive association between acute PM exposure and increased psychiatric emergency presentations indicated by emergency ambulance dispatches data. Children were more vulnerable and might develop psychiatric problems including those leading to suicide. Public awareness of the health risks of PM is important to strengthen current efforts to reduce emissions.