Spatial and temporal trends in the mortality burden of ozone pollution in China: 2005-2017

Abstract

Introduction: While recent assessments have quantified the burden of ozone pollution at the national scale in China, air quality managers would benefit from assessments that disaggregate health impacts over regions and over time. Taking advantage of a new daily maximum 8-hour averaged (MDA8) ozone concentration dataset, we analyze spatial and temporal trends of ozone-related mortality burden in China from 2005 to 2017. Methods: Population weighted exposure (PWE) was calculated by overlapping ozone concentrations and population maps. MDA8 ozone concentrations at 10 km resolution from 2005-2017 were from a nationwide prediction model that was based on the XGBoost algorithm and trained by MDA8 ozone observations from 2013 to 2017 combining with concurrent meteorological parameters and land use data. Population data are from Landscan Global Population Database. Using non-accidental total (NAT) deaths as target outcomes, we further calculated the excess deaths by applying exposure response functions from 272 Chinese cities. Results and Discussion: During 2005-2017, MDA8 ozone PWE fluctuated from 87.2 μg/m3 to 92.2 μg/m3, with no obvious upward or downward trends. National PWE are higher than the national average ozone concentration, indicating that the overlap of dense population areas and heavy polluted areas aggravated the mortality burdens. National ozone related NAT deaths increased from approximately 145,000 (95% confidence interval (CI): 70,000-213,000) cases in 2005 to 167,000 (95% CI: 80,000-245,000) cases in 2017. The mortality burden exhibited strong spatial variations, with high excess deaths concentrated in Beijing-Tianjin Metropolitan Region, North China Plain, Yangtze River Delta, Pearl River Delta, Sichuan Basin, Wuhan Metropolitan Region, and Changsha-Zhuzhou-Xiangtan. Hotspots of mortality burden have not expanded significantly over time, that is to say, the regions with heavy mortality burdens appear to be the ones with rapid growth. This undoubtedly makes the health risk of ozone in these areas more severe.