Physical activity alleviated associations of oxidation capacity of the atmosphere with platelet-based inflammatory indicators: findings from the Henan Rural Cohort Study

Abstract

Background: several adverse effects of ozone (O₃) and nitrogen dioxide (NO₂) are assessed using combined oxidant capacity (O_x) and redox-weighted oxidant capacity (O^wt_x) as surrogates. However, the associations of oxidant capacity (O_x and O^wt_x) with platelet-based inflammatory indicators and the potential modifying role of physical activity (PA) remain unclear. Methods: 31 318 participants were selected from the baseline survey of the Henan Rural Cohort Study. The O_x and O^wt_x were calculated based on O₃ and NO₂. The International Physical Activity Questionnaire was used to evaluate PA. Platelet-based inflammatory indicators were obtained from the data of physical examination. Generalized linear models were applied to explore associations between atmospheric oxidation capacity indicators (O₃, O_x, O^wt_x, and NO₂) and platelet-based inflammatory indicators and whether PA modified these associations. Results: O₃, O_x, and O^wt_x were positively associated with platelet-based inflammatory indicators (PCT, PLT, PLR, SII, MLR and SIRI). The estimated β values and 95% confidence intervals (CIs) for PLT in response to a 5 μg m⁻³ increment in O₃, O_x, and O^wt_x were 19.267 × 10⁹ L⁻¹ (95% CI: 17.493, 21.041 × 10⁹ L⁻¹), 6.226 × 10⁹ L⁻¹ (95% CI: 5.502, 6.950 × 10⁹ L⁻¹), and 14.664 × 10⁹ L⁻¹ (95% CI: 13.101, 16.227 × 10⁹ L⁻¹), respectively. The corresponding values for SIRI were 0.134 × 10⁹ L⁻¹ (95% CI: 0.111, 0.156 × 10⁹ L⁻¹), 0.064 × 10⁹ L⁻¹ (95% CI: 0.055, 0.073 × 10⁹ L⁻¹), and 0.135 × 10⁹ L⁻¹ (95% CI: 0.115, 0.155 × 10⁹ L⁻¹). And similar results were observed for NO₂. Furthermore, we observed positive associations of O₃, O_x, O^wt_x, and NO₂ with platelet-based inflammatory indicators attenuated by increased PA levels. Conclusions: exposure to O₃, O_x, O^wt_x, and NO₂ was positively associated with platelet-based inflammatory indicators, and these associations were modified by PA. The findings suggested that a healthy lifestyle of PA might be an effective measure against early adverse effects of air pollution.