An association between fine particulate matter (PM_2.5) levels and emergency ambulance dispatches for cardiovascular diseases in Japan

Purpose: The aim of this study is to determine whether short-term exposure to fine particulate matter (PM_2.5) is associated with emergency ambulance dispatches for cardiovascular diseases in Japan. Methods: The nationwide data on emergency dispatches of ambulance for cardiovascular diseases classified as I00–I99 by International Classification of Diseases-10th revision in 30 Japanese prefectures between April 1 and December 31, in 2010 were analyzed. Data on weather variability including PM_2.5, temperature and relative humidity were acquired from ambient air pollution monitoring stations. Conditional Poisson regression models were used to estimate the prefecture-specific effects of PM_2.5 on morbidity, and adjust for confounding factors. A meta-analysis was then applied to pool estimates at the 30-prefecture level. Results: A total of 160,566 emergency ambulance dispatches for cardiovascular diseases were reported during the study period. The risk of emergency ambulance dispatch for cardiovascular diseases significantly increased with an increase in the exposure to PM_2.5 in Fukuoka and Iwate Prefectures. However, we found no statistically significant associations between PM_2.5 and emergency ambulance dispatches in the pooled analysis (odds ratio 1.00, 95 % confidence interval 0.99–1.00). Heterogeneity was not observed between prefectures (Cochran Q test, p = 0.187, I² = 18.4 %). Conclusions: Exposure to PM_2.5 is not associated with overall emergency ambulance dispatches for cardiovascular diseases in Japan.