[Impact of fine particulate matter exposure on non-accidental mortality under different apparent temperature levels]

To assess the impact of exposure to particulate matter with aerodynamic diameter ≤2.5 μm (PM_2.5) on non-accidental mortality under different apparent temperature levels and to further explore the modification effect of apparent temperature.

This study used time-series design. Tianjin and Ningbo from China, Bangkok and Chiang Mai from Thailand were selected as the research sites, and the apparent temperature was applied as the exposure index. Through the quantitative estimation of the threshold temperature, the corresponding pollutant concentration was divided into high and low levels, and the generalized Poisson additive model was used to evaluate the association between PM_2.5 exposure and non-accidental death of residents at different temperature levels.

The ave-rage concentrations of PM_2.5 in Tianjin, Ningbo, Bangkok, and Chiang Mai during the study period were (73.6±35.6), (48.0±32.1), (33.5±28.4) and (32.6±28.6) μg/m³, respectively; the average daily non-accidental death counts were 148, 57, 28, and 8. The analysis of the generalized Poisson additive model showed that the daily non-accidental death counts increased by 0.43% (95%CI: 0.33%-0.54%) per 10 μg/m³ increase of PM_2.5 in lag 0 day in Tianjin of China; 0.27% (95%CI: 0.08%-0.46%) per 10 μg/m³ increase of PM_2.5 in lag 2 days in Ningbo of China. The effect was magnified in high temperature levels in Tianjin and in low temperatures in Ningbo and Bangkok. The mortality effect of PM_2.5 in various temperature levels stayed still in co-pollutant regression models.

Exposure to fine particulate matter had an adverse effect on non-accidental mortality, which reminded us to give further attention to the pollution control. The findings also indicated that apparent temperature might modify mortality effects of PM_2.5 and the modification effect varied in different regions. Protective policies due to regional differences should be made and more scientific and social attention on mutual effect of air pollution and climate change needs to be appealed.