Moderate-vigorous physical activity (MVPA) is known to reduce the risk of cardiovascular disease (CVD), but its role in mitigating or exacerbating this risk under exposure to air pollution remains unclear. This study investigates the associations between MVPA and CVD in the context of air pollution among both sexes.

This nationwide, cross-sectional study included 17,138 middle-aged and elderly people from the 2018 wave of the China Health and Retirement Longitudinal Study. Physical activity was assessed using the International Physical Activity Questionnaire. Data on air pollutants, including particulate matter, sulfur dioxide, ozone, nitrogen dioxide, carbon monoxide, and air quality index, were obtained from the China High Air Pollutants dataset and the Science Data Bank. CVD was identified based on self-reported physician diagnoses of heart disease or stroke.

More physically active participants were associated with lower CVD prevalence, while all air pollutants were linked to higher prevalence in the top exposure quartile. Physically inactive individuals exhibited the highest CVD prevalence across different levels of air pollution. Under high levels of air pollution, MVPA generally exhibited an inverse association with CVD prevalence in males (P for overall < 0.05), but not in females (P for overall > 0.05). In addition, MVPA duration positively mediated the associations between air pollutant exposure and CVD prevalence, with mediation proportions ranging from 10.10 to 33.30% in females and 5.14 to 7.53% in males.

This study highlights that, under high levels of air pollution, the inverse association between MVPA and CVD prevalence was generally observed among males. Moreover, MVPA mediates the relationships between all air pollutants and CVD prevalence.