Association between ambient particulate matter and hospitalization for anxiety in China: A multicity case-crossover study

Aims: Evidence concerning the impact of ambient particulate matter (PM) on mental health is just emerging and inconsistent. Air pollution with high PM levels has been frequently reported in China, however, no Chinese study has determined the association between PM exposures and anxiety hospitalizations. We examined the potential association between PM concentrations and anxiety admissions in 26 Chinese cities from January 2014 to December 2015. Methods: A time-stratified case-crossover design was employed in the study. Anxiety hospitalizations were identified according to ICD-10 from the electronic hospitalization summary reports system in China. Conditional logistic regression was applied to estimate the relation between PM levels and anxiety admissions, stratified by age and sex. Results: Positive associations between PM2.5/PM10 and admitted anxiety cases were observed. PM2.5 had the largest effect estimate at lag 5 days, with a per 10 mu g/m(3) increase corresponding to a 0.63% (95% CI, 0.26-1.00) increase in anxiety admissions. PM10's largest effect estimate was observed at lag 3 days, increasing 0.37% (95% CI, 0.12-0.62) anxiety admissions per 10 mu g/m(3). Females were more sensitive to PM2.5/PM10 concentrations than males, however, the effect modification by age was not significant. A marginally significant distinction in anxiety hospitalizations was found in patients with and without CVDs when they were exposed to PM2.5. Conclusions: Our findings indicate that short-term exposure to increased concentrations of PM2.5/PM10 exacerbates risks of anxiety hospitalizations in 26 Chinese cities. We observed effect modification by sex, with significantly stronger associations in female patients. This study offers the promise that reducing PM air pollution could probably reduce the huge disease burden from anxiety disorders.