Differential effects of size-specific particulate matter on emergency department visits for respiratory and cardiovascular diseases in Guangzhou, China

Abstract Background Studies differentiating the cardiorespiratory morbidity effects of PM 2.5 , PM 10 , and PM 2.5∼10 (i.e. coarse PM or PM c ) are still limited and inconsistent. Objective To estimate the acute, cumulative, and harvesting effects of exposure to the three size-specific PM on cardiorespiratory morbidity, and their concentration-response relations. Methods A total of 6,727,439 emergency department (ED) visits were collected from 16 public teaching hospitals in Guangzhou, from January 1st 2012 to December 31st 2015, among which over 2.1 million were asthma, COPD, pneumonia, respiratory tract infection (RTI), hypertension, stroke, and coronary heart disease (CHD). Distributed lag non-linear models (DLNM) was used to estimate the associations between the three size-specific PM and ED visits for the cardiovascular diseases. Long-term trends, seasonality, influenza epidemics, meteorological factors, and other gas pollutants, including SO2, NO 2 , and O 3 , were adjusted. We stratified the analyses by gender and age. Results Elevated PM 2.5 and PM 10 were significantly associated with increased ED visits for pneumonia, RTI, and CHD at both lag 0 and lag 0-3 . A 10 μg/m 3 increment of PM c (at lag 0-14 ) was estimated to increase ED visits for pneumonia by 6.32% (95% CI, 4.19, 8.49) and for RTI by 4.72% (95% CI, 3.81, 5.63), respectively. PM c showed stronger cumulative effects on asthma in children than elderly. We observed significant harvesting effects (i.e. morbidity displacements) of the three size-specific PM on respiratory but very little on cardiovascular ED visits. The concentration-response curves suggested non-linear relations between exposures to the three different sizes of PM and respiratory morbidity. Conclusions Overall, the three size-specific PM demonstrated distinct acute and cumulative effects on the cardiorespiratory diseases. PM 2.5 and PM c would have significant effects on pneumonia and RTI. Strategies should be considered to further reduce levels of ambient PM 2.5 and PM c .