Association between short-term exposure to ambient air pollution and dementia mortality in Chinese adults.

BACKGROUND:Short-term exposure to ambient air pollution has been linked to an increased risk of mortality from a variety of causes, but its effects on mortality from dementia remain largely unknown. OBJECTIVES:To investigate the association between short-term exposure to ambient air pollution and dementia mortality, and quantitatively assess the excess mortality. METHODS:In this time-stratified case-crossover study, 47,108 dementia deaths were identified in Jiangsu province, China during 2015-2019. Exposure to particulate matter with an aerodynamic diameter ≤ 2.5 μm (PM2.5), PM10, sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), and ozone (O3) was assessed by extracting daily concentrations from a validated grid dataset based on each subject's residential address. Conditional logistic regression models were applied for exposure-response analyses. RESULTS:There were 47,108 case days and 159,852 control days during the study period. Each 10 μg/m3 increase of lag 04-day exposure to PM2.5, PM10, and NO2 was significantly associated with a 1.43 % (95 % CI: 0.77, 2.09 %), 1.06 % (0.59, 1.54 %), and 2.80 % (1.51, 4.10 %) increase in odds of dementia mortality, corresponding to an excess mortality of 4.87 %, 5.50 %, and 6.43 %, respectively. We estimated that reducing ambient air pollutant exposures to the WHO air quality guidelines would avoid up to 4.17 % of the dementia deaths, while the ambient air quality standards in China would only help avoid up to 0.39 %. CONCLUSIONS:This study provides consistent evidence that short-term exposure to PM2.5, PM10, and NO2 is associated with increased odds of dementia mortality, which can be translated to a considerable excess mortality. Our findings highlight a potential approach to prevent deaths from dementia by reducing individual exposures to ambient air pollution, especially in areas with high levels of ambient air pollution.