Identification of Health Effects of Complex Air Pollution in China

Abstract With the progress of air pollution control in China, the concentration of particulate matter has decreased, but the concentration of ozone has increased, the problem of complex air pollution has become more severe, posing a serious threat to public health. However, there is less study on the health effects of complex air pollution in China. Instead of introducing pollutant concentrations directly, we converted them into a set of predictors to prevent collinearity and other problems will occur when the concentrations of multiple correlated pollutants are introduced in general multi-pollution models. Based on different combinations of PM 2.5 , NO 2, and O 3 concentration levels, air pollutant constituent condition is divided into eight types, including three single-pollutant types and four multi-pollutant types. The health effects of different pollution types on mortality in eight typical Chinese cities from 2013 to 2016 were evaluated using a generalized additive model. The results from eight cities collectively indicate that multi-pollutant type leads to a higher impact on mortality risk than single-pollutant type. Type 7 with higher PM 2.5 , O 3 , and NO 2 and type 4 with higher PM 2.5 and NO 2 have a greater relative risk among them. In most northern cities, the multi-pollutant type has a higher mortality effect in the warm season, but the single-pollutant type with high PM 2.5 has a higher effect in the cold season. In southeastern cities, the multi-pollutant type had a higher mortality effect in both seasons. The results also showed that the excess risk of multi-pollutants was less than the simple sum of individual air pollutants effects, partially false conclusions would have been reached by ignoring the presence of interactions between air pollutants. The result further highlights the urgency and necessity of moving towards a multi-pollutant approach in air pollution health research under the background of atmospheric emission reduction and global warming.