Meimei Xu1, Hind Sbihi2, Xiaochuan Pan3, Michael Brauer4. 1. Institute of Medical Information & Library, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100020, China. 2. BC Children's Hospital Research Institute, Vancouver, BC, V6H 3N1, Canada; School of Population and Public Health, Faculty of Medicine, The University of British Columbia, Vancouver, BC, V6T 1Z3, Canada. 3. Department of Occupational and Environmental Health, School of Public Health, Peking University, Beijing, 100191, China. Electronic address: xcpan@hsc.pku.edu.cn. 4. School of Population and Public Health, Faculty of Medicine, The University of British Columbia, Vancouver, BC, V6T 1Z3, Canada. Electronic address: michael.brauer@ubc.ca.
Abstract
INTRODUCTION: Epidemiologic studies have reported associations between short-term exposure to particulate matter <2.5 μm in aerodynamic diameter (PM2.5) and mortality, but the role of modifiers remains unclear with studies reporting inconsistent results. We evaluated the impact of individual (age, gender and education) and township (geographic area, socioeconomic status, background air pollution and road density) level factors on the relationship between short-term variation in PM2.5 with cause-specific mortality in Beijing (population: 21.7 million in 2016), China. METHODS: Daily PM2.5 concentrations in each township (n = 327; township population: 2000-359,400; township area: 1-392 km2) within Beijing were estimated by kriging with external drift using measurements from 35 air quality monitoring stations and geographic variables. Time-stratified case-crossover analysis with township-level mortality data from Oct. 1st, 2012 to Dec. 31st, 2013 was then used to examine associations between PM2.5 exposure estimates and cause-specific mortality, stratified by the potential effect modifiers. RESULTS: A 10-μg/m3 increase in PM2.5 concentration was associated with a 0.17% [95% confidence interval (CI): 0.05%-0.29%] and 0.27% (95%CI:0.01%-0.52%) increase in non-accidental and stroke mortality with no lag, a 0.81% (95%CI:0.39%-1.23%) and 0.96% (95%CI:0.35%-1.57%) increase in respiratory disease (RD) and chronic obstructive pulmonary disease (COPD) mortality at a lag of two-day moving average. For individual-level effect modifiers, the elderly showed higher effects for all the specific causes of mortality; those with lower education level showed higher effects for non-accidental, cardiovascular disease and stroke mortality; females showed higher effects for non-accidental and cause-specific cardiovascular diseases. For township-level effect modifiers, effect estimates tended to be larger for suburban areas, areas of lower road density, lower PM2.5 and lower socioeconomic status. CONCLUSIONS: Short-term exposure to township-level ambient PM2.5 was associated with increased mortality in Beijing, with indications of effect modification by both individual and township-level factors.
INTRODUCTION: Epidemiologic studies have reported associations between short-term exposure to particulate matter <2.5 μm in aerodynamic diameter (PM2.5) and mortality, but the role of modifiers remains unclear with studies reporting inconsistent results. We evaluated the impact of individual (age, gender and education) and township (geographic area, socioeconomic status, background air pollution and road density) level factors on the relationship between short-term variation in PM2.5 with cause-specific mortality in Beijing (population: 21.7 million in 2016), China. METHODS: Daily PM2.5 concentrations in each township (n = 327; township population: 2000-359,400; township area: 1-392 km2) within Beijing were estimated by kriging with external drift using measurements from 35 air quality monitoring stations and geographic variables. Time-stratified case-crossover analysis with township-level mortality data from Oct. 1st, 2012 to Dec. 31st, 2013 was then used to examine associations between PM2.5 exposure estimates and cause-specific mortality, stratified by the potential effect modifiers. RESULTS: A 10-μg/m3 increase in PM2.5 concentration was associated with a 0.17% [95% confidence interval (CI): 0.05%-0.29%] and 0.27% (95%CI:0.01%-0.52%) increase in non-accidental and strokemortality with no lag, a 0.81% (95%CI:0.39%-1.23%) and 0.96% (95%CI:0.35%-1.57%) increase in respiratory disease (RD) and chronic obstructive pulmonary disease (COPD) mortality at a lag of two-day moving average. For individual-level effect modifiers, the elderly showed higher effects for all the specific causes of mortality; those with lower education level showed higher effects for non-accidental, cardiovascular disease and strokemortality; females showed higher effects for non-accidental and cause-specific cardiovascular diseases. For township-level effect modifiers, effect estimates tended to be larger for suburban areas, areas of lower road density, lower PM2.5 and lower socioeconomic status. CONCLUSIONS: Short-term exposure to township-level ambient PM2.5 was associated with increased mortality in Beijing, with indications of effect modification by both individual and township-level factors.