| Objective 1) To determine the short-term interactive effects of temperature and air pollutants on mortality; 2) To find the vulnerable people of health risks associated with exposure to air pollution and temperature; 3) To compare the interactive effects of temperature and air pollutants between different citiesMethods The data of daily mortality were obtained from 2011 to 2013 in Ningbo city, and the corresponding meteorological data and ambient air pollution data were also collected. Time series analysis with distributed lag non-linear models were employed to examine the lag effects of air pollutions or temperature on mortality, and the methods of response surface and temperature stratification were used to analysis the interactive effects between temperature and air pollution. Stratified analysis were used to screen the sensitive disease and vulnerable people; and case-crossover study were conducted to verify the results of time series study.Results 1) In Ningbo City, both temperature and air pollution had been generally rising in recent decades. 2) We found the effect of heat tended to be immediate, while the impact of cold lasted longer; women, mateless, the elderly and people with low level of education had a higher risk of temperature. 3) A 10μg/m3 increase of PM10 associated with an increase of 0.34% (95% CI: 0.11, 0.57), 0.24% (95% CI: -0.15,0.64)and 0.49% (95% CI: 0.00, 0.99) in non-accidental, cardiovascular and respiratory mortality over cumulative lag of 0-2 days. In low, medium and high temperature levels,which were stratified by the daily mean temperature of 10th and 90th, a 10μg/m3 increase of PM10 result in the excess mortality were 0.83% (95% CI: 0.18, 1.49), 0.49 %(95% CI: 0.24, 0.75) and 2.39% (95% CI: 0.78, 4.02), respectively. The interactive effect between PM 10 and high temperature was statistical significance (P<0.05),particularly in mateless, the elderly and people with low level of education groups. 4)A 10μg/m3 increase of SO2 associated with an increase of 1.49% (95% CI: 0.00, 2.99),3.01% (95% Cl: 0.43, 5.66) and 1.14% (95% CI: -2.01, 4.40) in no non-accidental,cardiovascular and respiratory mortality over cumulative lag of 0-4 days. In low,medium and high temperature levels, which were stratified by the daily mean temperature of 10th and 90th, a 10μg/m3 increase of SO2 result in the excess mortality were 2.00% (95% CI: 0.20, 3.84), 3.61% (95% CI: 2.19, 5.05) and 13.18% (95% CI:1.00, 26.84), respectively. The interactive effect between SO2 and temperature was suggestive (P<0.20), particularly in male, mateless, the elderly and people with low level of education groups. 5) In low, medium and high temperature levels, which were stratified by the daily mean temperature of 10th and 90th, the interactive effect between NO2 and temperature was suggestive (P<0.20), but not in the multi-pollutant model. 6)Multi-cities results suggest that the interactive effect had presented some region discrepancy, for instance, the effects of API were higher in high temperature in Ningbo and Beijing, while were higher in both low and high temperature in Guangzhou city,however, the interactive effect were not found in Shanghai.Conclusion We found increasing trends of temperature and air pollution in recent years and interactive effects between them on mortality in Ningbo city, in terms of the background of global warming, which would pose risks on human health greatly in the future. Vulnerable people, such as elderly should be paid more attention to protect them from air pollution in high temperature. |
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