Peking University, October 18, 2016: Recently, a study shows that in 2013, premature mortalities attributed to PM2.5 nationwide were 1.37 million in total. 83% of China’s population were exposed in areas where the yearly average concentration of PM2.5 exceeded 35 micrograms per cubic meter, the upper limit set in Ambient air quality standards. The study is the first to estimate the assimilated spatial PM2.5 concentrations across China based on direct PM2.5 measurements from 506 PM2.5 monitoring sites and a regional air quality model, using the integrated exposure-response model.Science of the Total Environment (STOTEN) published the paper “Estimating adult mortality attributable to PM2.5 exposure in China with assimilated PM2.5 concentrations based on a ground monitoring network ”  with professor Zhu Tong from College of Environmental Sciences and Engineering, Peking University, and researcher Zhu Jiang from Institute of Atmospheric Physics, Chinese Academy of Sciences as co-corresponding authors.
 
For its significant influence on human health, study on the health riskof atmospheric particulate matter is of great importance for the establishment of environmental criteria and decision on emission reduction. Despite some previous work on the risk evaluation of premature death resulted from PM2.5 exposure, controversy still exists due to different exposure assessments and choices of the concentration-response function. Among these studies, some used the statistics of scattering city sites to represent the data of the nation; others combined satellite remote sensing and retrieval mode to calculate the concentration of PM2.5 at ground level. The results thus fluctuate from 0.35 to 1.60 million people per year. Since 2013 when China first introduced PM2.5 into the regular monitoring system, a large sum of data has been accumulated, making it possible for high-quality study on PM2.5 exposure impact.
 
From 2014, professor Zhu Tong has been working hand in glove with Zhu Jiang. They use the data on PM2.5 of over 500 ground observation stations, re-analyze them with the Nested Air Quality Prediction Modeling System (NAQPMS), adopt the newly developed integrated exposure–response (IER) model, and finally estimate the risk of premature death due to exposure to PM2.5. They also quantify the mortality benefits when the concentration of PM2.5 in China meet the WHO IT-1, IT-2, IT-3 (35, 25 and 15 micrograms per cubic meter) and AQG (10 micrograms per cubic meter set by World Health Organization(WHO) respectively.

Left: distribution of premature death due to PM2.5 exposure in 2013
Right: mortality benefits when the concentration of PM2.5 meet 35, 25, 15 and 10 micrograms per cubic meter respectively
 
Research shows that ischemic heart disease, cerebrovascular disease, chronic obstructive pulmonary disease and lung cancer account for 28%, 50%, 12% and 10% respectively among the 1.37 million premature deaths. Megacities with high concentration of PM2.5 and great population density are regions with the highest risk. The study also points out that if the concentration of PM2.5 meets the WHO standards, the risk of premature death can decrease by 23%, 39%, 66% and 83% respectively, revealing the non-linear relationship between the decrease of PM2.5 and the improvement of health condition. Economic conditions permitting, it is necessary to raise ambient air quality standards in the future for people’s health.
 
Written by: Zhou Yijing
Edited by: Yan Shengnan
Source: College of Environmental Science and Engineering