Acute effect of ozone on daily stroke mortality in 88 districts/counties of China

ObjectiveTo explore the acute effect of ozone on daily stroke mortality in 88 districts/counties of China.

MethodsDaily stroke mortality and environment data from 2015 to 2018 in 88 districts/counties of China were collected to perform a time-series analysis. First, we linked Quasi-Poisson distribution with generalized additive model to evaluate the effect of ozone on daily stroke mortality in each districts/counties after adjusting the long-term and seasonal trend as well as meteorological factors and the effect of “days of week”. Then, we used random-effect models to pool districts/counties-specific estimates and obtain overall average summary estimates of acute effect of ozone on stroke mortality. We also conducted stratification analyses by regional, seasonal and demographic factors (sex and age).

ResultsAt the overall average level, a 10 μg/m³ increase in ozone concentration (lag1) was associated with 0.30% of risk increase of daily mortality form stroke (95% CI : 0.13%-0.47%). At the area specific average level, the acute effect was strongest in the districts/counties in southern China, and the estimate was 0.74% (95% CI : 0.08%-1.40%). Sex specific analysis indicated that each 10 μg/m³ increase in ozone concentration was associated with an increase of 0.38% (95% CI: 0.13%-0.63%) and 0.23% (95% CI: 0.002%-0.460%) of daily stroke mortality in females and males, respectively. The association were stronger in warm season and in older people. However, there were no statistically significant differences in associations between ozone and daily stroke mortality according to region, season, sex and age.

ConclusionThe increase in air ozone concentration can increase the risk of stroke mortality. It is necessary to strengthen the prevention and control of ozone pollution.