Hualiang Lin1, Xiaojie Wang2, Zhengmin Min Qian3, Shu Guo4, Zhenjiang Yao5, Michael G Vaughn3, Guanghui Dong6, Tao Liu7, Jianpeng Xiao7, Xing Li7, Weilin Zeng7, Yanjun Xu8, Wenjun Ma9. 1. Department of Medical Statistics and Epidemiology, School of Public Health, Sun Yat-sen University, Guangzhou 510080, China. 2. School of Public Health, Guangdong Pharmaceutical University, Guangzhou, China; Guangdong Provincial Institute of Public Health, Guangdong Provincial Center for Disease Control and Prevention, Guangzhou 511430, China. 3. College for Public Health and Social Justice, Saint Louis University, Saint Louis, MO 63104, USA. 4. South China Institute of Environmental Sciences, Ministry of Environmental Protection, Guangzhou, China. 5. School of Public Health, Guangdong Pharmaceutical University, Guangzhou, China. 6. Department of Environmental and Occupational Health, School of Public Health, Sun Yat-Sen University, Guangzhou, China. 7. Guangdong Provincial Institute of Public Health, Guangdong Provincial Center for Disease Control and Prevention, Guangzhou 511430, China. 8. Guangdong Provincial Center for Disease Control and Prevention, Guangzhou 511430, China. 9. Guangdong Provincial Institute of Public Health, Guangdong Provincial Center for Disease Control and Prevention, Guangzhou 511430, China. Electronic address: mawj@gdiph.org.cn.
Abstract
BACKGROUND: Daily mean concentration cannot fully address the hourly variations of air pollution within one day. As such, we proposed a new indicator, daily exceedance concentration hours (DECH), to explore the acute cardiovascular effects of ambient PM2.5 (particles with aerodynamic diameters less than 2.5μm). The DECH in PM2.5 was defined as daily total concentration-hours >25μg/m3. METHODS: A generalized additive model with a quasi-Poisson link was applied to estimate the associations between day-to-day variation in PM2.5 DECH and day-to-day variation in cardiovascular mortality in six subtropical cities in Guangdong Province, China. RESULTS: The analysis revealed significant associations between PM2.5 DECHs and cardiovascular mortality. A 500μg/m3∗h increase in PM2.5 DECHs at lag03 was associated with an increase of 4.55% (95% confidence interval (CI): 3.59%, 5.52%) in cardiovascular mortality, 4.45% (95% CI: 2.81%, 6.12%) in ischemic cardiovascular mortality, 5.02% (95% CI: 3.41%, 6.65%) in cerebrovascular mortality, and 3.00% (95% CI: 1.13%, 4.90%) in acute myocardial infarction mortality. We further observed a greater mortality burden using PM2.5 DECHs than daily mean PM2.5 (6478 (95% CI: 5071, 7917) VS 5136 (95% CI: 3990, 6305)). CONCLUSION: This study reveals that PM2.5 DECH is one important exposure indicator of ambient PM2.5 to measure its cardiovascular mortality effects in Pearl River Delta region; and that using daily mean concentration could under-estimate the mortality burden compared with this new indicator.
BACKGROUND: Daily mean concentration cannot fully address the hourly variations of air pollution within one day. As such, we proposed a new indicator, daily exceedance concentration hours (DECH), to explore the acute cardiovascular effects of ambient PM2.5 (particles with aerodynamic diameters less than 2.5μm). The DECH in PM2.5 was defined as daily total concentration-hours >25μg/m3. METHODS: A generalized additive model with a quasi-Poisson link was applied to estimate the associations between day-to-day variation in PM2.5 DECH and day-to-day variation in cardiovascular mortality in six subtropical cities in Guangdong Province, China. RESULTS: The analysis revealed significant associations between PM2.5 DECHs and cardiovascular mortality. A 500μg/m3∗h increase in PM2.5 DECHs at lag03 was associated with an increase of 4.55% (95% confidence interval (CI): 3.59%, 5.52%) in cardiovascular mortality, 4.45% (95% CI: 2.81%, 6.12%) in ischemic cardiovascular mortality, 5.02% (95% CI: 3.41%, 6.65%) in cerebrovascular mortality, and 3.00% (95% CI: 1.13%, 4.90%) in acute myocardial infarction mortality. We further observed a greater mortality burden using PM2.5 DECHs than daily mean PM2.5 (6478 (95% CI: 5071, 7917) VS 5136 (95% CI: 3990, 6305)). CONCLUSION: This study reveals that PM2.5 DECH is one important exposure indicator of ambient PM2.5 to measure its cardiovascular mortality effects in Pearl River Delta region; and that using daily mean concentration could under-estimate the mortality burden compared with this new indicator.