Impact of ambient ozone exposure on death from cardiovascular and cerebrovascular diseases in Minhang District, Shanghai

Background Ozone (O₃) pollution has gradually become a primary problem of air pollution in recent years. Conducting epidemiological studies on the correlation between O₃ concentration variation and risk of cardiovascular and cerebrovascular diseases can provide reference data for O₃ risk assessment and related policy making.

Objective To quantitatively evaluate the effects of O₃ exposure on mortalities of cardiovascular and cerebrovascular diseases among residents in Minhang District, Shanghai.

Methods Data of mortalities of cardiovascular and cerebrovascular diseases, air pollutants, and meteorological factors in Minhang District of Shanghai from January 1, 2016 to December 31, 2021 were collected. Associations between O₃ concentration and the mortalities due to total cardiovascular and cerebrovascular diseases, coronary heart disease, and stroke were analyzed by generalized additive models with a quasi Poisson distribution with different lag patterns, such as current day effect (lag0), single-day lag effects (lag1-lag3), and cumulative lag effects (lag01-lag03). The subgroup analyses of age, sex, and season were conducted. Furthermore, temperature was divided into low, middle, and high levels based on the 25th percentile (P₂₅) and the 75th percentile (P₇₅) to perform hierarchical analyses. Increased excess risks (ER) of death from target diseases caused by a 10 µg·m⁻³ increase in daily maximum 8 h concentration of O₃ (O₃-8 h) and their 95% confidence intervals (CI) were used to indicate the effects of O₃.

Results The associations between O₃ and the risks of death from cardiovascular and cerebrovascular diseases were statistically significant at lag2, lag3, lag02, and lag03 (P<0.05), with the greatest effect size observed at lag03. The ER values of death from cardiovascular and cerebrovascular diseases in general population, male residents, and people aged 65 years and older, from coronary heart disease in male residents, and from stroke in general population increased by 1.02% (95%CI: 0.36%, 1.69%), 1.40% (95%CI: 0.47%, 2.34%), 0.87% (95%CI: 0.19%, 1.55%), 1.96% (95%CI: 0.49%, 3.44%), and 1.02% (95%CI: 0.07%, 1.98%) for a 10 µg·m⁻³ increase in O₃-8 h concentration at lag03, respectively. During the warm season (from April 1 to September 30), the ER values of death from cardiovascular and cerebrovascular diseases and coronary heart disease per 10 µg·m⁻³ increase in O₃ were 1.18% (95%CI: 0.33%, 3.33%) and 2.69% (95%CI: 0.39%, 5.03%), while the O₃ effect was only statistically significant on cardiovascular and cerebrovascular diseases during the cold season (from October 1 to March 31 next year). At the middle and high temperature levels, the ER values of death from cardiovascular and cerebrovascular diseases increased by 1.63% (95%CI: 0.32%, 2.96%) and 1.14% (95%CI: 0.17%, 2.12%) respectively. The two-pollutant models showed similar results after including other pollutants (carbon monoxide, nitrogen dioxide, sulfur dioxide, fine particulate matter, or inhalable particulate matter).

Conclusion Ambient O₃ pollution may increase the mortality risks of cardiovascular and cerebrovascular diseases, coronary heart disease, and stroke in Minhang District of Shanghai.