Physical activity in the relationship between multiple air pollutants exposure and risk of hypertension: a prospective cohort study in China

This study is targeted to explore the relationship between exposure to various air pollutants (PM₁, PM_2.5, PM₁₀, O₃, and NO₂) and hypertension risk, and to assess the role of physical activity in this relationship among Chinese adults. The association between multiple ambient air pollutants (with separate models for each pollutant) and hypertension was explored using time-varying Cox proportional hazards regression models, adjusted for season, spatial autocorrelation, demographic, socioeconomic, and behavioral factors. The median follow-up was 4 years. The interaction tests revealed significant interactions between physical activity and exposure to PM₁, PM_2.5, PM₁₀, and NO₂, but not for O₃ (P > 0.05). Physically active participants did not show significant increases in hypertension risk from pollutants. In contrast, inactive participants faced higher risks: PM₁ (12.9%), PM_2.5 (6.0%), PM₁₀ (5.0%), NO₂ (17.0%). Finally, in the multiple pollutant models, controlling for NO₂ nullified the significance of PM₁ and PM_2.5, while adjusting for O₃ increased their HRs. PM₁₀ and O₃ remained significant in all models, and adjusting for PM10 or both PM₁₀ and O₃ eliminated the significance of NO₂. Higher concentrations of air pollution were linked to a heightened risk of developing hypertension among Chinese adults; however, physical activity may help mitigate this elevated risk.