Long-term exposures to ozone and nitrogen dioxide and all-cause, cardio/cerebrovascular disease mortalities in China, 2010−2021

Objective To analyze the impacts of long-term exposures to ozone and nitrogen dioxide on the all-cause mortality and cardio/cerebrovascular mortality in China from 2010 to 2021.

Methods The risk factor information of the study participants were obtained from the China Chronic Disease and Risk Factor Surveillance Project during 2010 - 2013, and the death information of the study participants verified by ID were obtained from national death cause surveillance system, and the pollutant concentration were collected from national air quality aurveillance network for the construction of grid information with a spatial resolution of 1 km × 1 km by using random forest model. COX proportional hazards model was used to calculate the risk ratio (HR) of the impact of ozone and nitrogen dioxide exposures on mortality and their 95% confidence interval (CI) after controlling for confounding variables, such as gender, age, smoking status, and alcohol consumption.

Results From 2010 to 2021, a total of 9136 (5.11%) deaths occurred in the study participants, of which 4086 (2.28%) were due to cardio/cerebrovascular diseases. The single pollutant model showed that long-term ozone exposure had no significant impact on all-cause mortality or cardio/cerebrovascular disease mortality (P>0.05). After adjusting for fine particulate matter (PM_2.5), the corresponding mortality risks increased significantly (HR_all-cause=1.01, HR_{cardio/cerebrovascular disease}=1.01). In the single pollutant model, a 10 μg/m³ increase in the concentration of nitrogen dioxide was associated with a 1.00% increase in the risk for all-cause mortality (HR=1.01, 95%CI: 1.00−1.02) and a 2.00% increase in the risk for cardio/cerebrovascular disease mortality (HR=1.02, 95%CI: 1.01−1.03). After adjusting for PM_2.5, the corresponding mortality risks increased (HR_all-cause=1.07, HR_{cardio/cerebrovascular disease}=1.06). The stratified analysis showed that ozone and nitrogen dioxide exposures had significant impacts on all-cause mortality and cardio/cerebrovascular disease mortality in women, the elderly aged ≥65 years and rural population.

Conclusion Long-term exposures to ozone and nitrogen dioxide can significantly increase the risk of all-cause mortality and cardio/cerebrovascular disease mortality in general population. Women, the elderly, smokers, and people living in rural areas are groups at high risk for air pollution. Therefore, it is of great importance to further strengthen air pollution control and related disease prevention and control.