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Compared with daily mean concentration of air pollution, hourly peak concentration may be more directly relevant to the acute health effects due to the high concentration levels, however, few have analyzed the acute mortality effects of hourly peak levels of air pollution. We examined the associations of hourly peak concentration of fine particulate matter air pollution (PM 2.5 ) with mortality in six cities in Pearl River Delta, China. We used generalized additive Poisson models to examine the associations with adjustment for potential confounders in each city. We further applied random-effects meta-analyses to estimate the regional overall effects. We further estimated the mortality burden attributable to hourly peak and daily mean PM 2.5 . We observed significant associations between hourly peak PM 2.5 and mortality. Each 10 μg/m3 increase in 4-day averaged (lag 03 ) hourly peak PM 2.5 corresponded to a 0.9% [95% confidence interval (CI): 0.7%, 1.1%] increase in total mortality, 1.2% (95% CI: 1.0%, 1.5%) in cardiovascular mortality, and 0.7% (95% CI: 0.2%, 1.1%) in respiratory mortality. We observed a greater mortality burden using hourly peak PM 2.5 than daily mean PM 2.5 , with an estimated 12915 (95% CI: 9922, 15949) premature deaths attributable to hourly peak PM 2.5 , and 7951 (95% CI: 5067, 10890) to daily mean PM 2.5 in the Pearl River Delta (PRD) region during the study period. This study suggests that hourly peak PM 2.5 might be one important risk factor of mortality in PRD region of China; the finding provides important information for future air pollution management and epidemiological studies. [ABSTRACT FROM AUTHOR]

Background Epidemiological studies have reported significant association between ambient fine particulate matter air pollution (PM 2.5 ) and mortality, however, few studies have investigated the relationship of mortality with PM 2.5 and associated mortality burden in China, especially in a multicity setting. Methods We investigated the PM 2.5 -mortality association in six cities of the Pearl River Delta region from 2013 to 2015. We used generalized additive Poisson models incorporating penalized smoothing splines to control for temporal trend, temperature, and relative humidity. We applied meta-analyses using random-effects models to pool the effect estimates in the six cities. We also examined these associations in stratified analyses by sex, age group, education level and location of death. We further estimated the mortality burden (attributable fraction and attributable mortality) due to ambient PM 2.5 exposures. Results During the study period, a total of 316,305 deaths were recorded in the study area. The analysis revealed a significant association between PM 2.5 and mortality. Specifically, a 10 μg/m 3 increase in 4-day averaged (lag 03 ) PM 2.5 concentration corresponded to a 1.76% (95% confidence interval (CI): 1.47%, 2.06%) increase in total mortality, 2.19% (95% CI: 1.80%, 2.59%) in cardiovascular mortality, and 1.68% (95% CI: 1.00%, 2.37%) in respiratory mortality. The results were generally robust to model specifications and adjustment of gaseous air pollutants. We estimated that 0.56% (95% CI: 0.47%, 0.66%) and 3.79% (95% CI: 3.14%, 4.45%) of all-cause mortalities were attributable to PM 2.5 using China's and WHO's air quality standards as the reference, corresponding to 1661 (95% CI: 1379, 1946) and 11,176 (95% CI: 9261, 13,120) attributable premature mortalities, respectively. Conclusion This analysis adds to the growing body of evidence linking PM 2.5 with daily mortality, and mortality burdens, particularly in one Chinese region with high levels of air pollution. [ABSTRACT FROM AUTHOR]