Objective Photochemical pollution has become a major concern in urban areas throughout China as ozone (O3) has been linked to increased residents' deaths. Therefore, this study aims to evaluate the acute effect of O3 on the circulatory death of residents in Baotou City.
Methods Daily meteorological data (average temperature, average relatve humidity, average air pressure, and average wind speed), selected air pollutants (PM2.5, PM10, SO2, CO, and O3), and populaton circulatory deaths in Baotou City from January 1, 2015 to December 31, 2017 were collected and analyzed descriptvely. Afer controlling long-term trend, meteorological factors, and day-of-the-week effect, a generalized linear model based on quasi-Poisson regression was used to analyze the potental associaton between O3 concentraton and daily populaton death from circulatory diseases. The excess risk and 95% confidence interval of mortality due to circulatory diseases were calculated for per 10 μg/m3 increase in O3.
Results The daily O3 levels in Baotou city in the whole year, summer, and winter were 93.94, 138.70, and 52.51 μg/m3, respectively. The results of single pollutant model showed that the circulatory disease mortality of general populaton (lag1), female residents (lag1), residents over 65 years old (lag1), and male residents (lag5) increased by 1.62% (95%CI:0.38%-2.88%), 2.16% (95%CI:0.48%-3.86%), 1.54% (95%CI:0.17%-2.92%), and 1.61% (95%CI:0.27%-2.96%) for per 10 μg/m3 increase in O3, respectively. The results of multi-pollutant model for the whole year showed that when SO2, CO, and PM2.5 were introduced separately or SO2, CO, PM2.5, and PM10 were introduced at the same tme, the daily death risk of circulatory diseases associated with O3 in general populaton, female residents, and residents over 65 years old were increased; when PM10 was introduced alone, the risk was reduced in general populaton and female residents, and increased in residents over 65 years old; when CO was introduced alone or SO2, CO, PM2.5, and PM10 were introduced at the same tme, the risk in male residents remained statstcally signifcant. The results of mult-pollutant model for summer showed that when SO2 was controlled alone or SO2, CO, PM2.5, and PM10 were controlled at the same tme, the risk of death from circulatory diseases in female residents were elevated.
Conclusion O3 polluton has an acute effect on the circulatory death of the residents in Baotou City, and the effect is stronger in summer than in winter.
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