Combined oxidant capacity, redox-weighted oxidant capacity and elevated blood pressure: A panel study

Evidence is limited on the potential health effects of O_x (sum value) and O_x^wt(weighted value), the two surrogates for ozone (O₃) and nitrogen dioxides (NO₂).

To investigate the impacts of O_x and redox-weighted oxidant capacity (O_x^wt) on blood pressure (BP).

A panel study was conducted with four repeated follow-up visits among 40 healthy college students in Hefei, Anhui Province, China from August to October, 2021. We measured BP by using an automated sphygmomanometer and obtained hourly data of air pollutants at a nearby site. The sum of O₃ and NO₂ (O_x) and their weighted average (O_x^wt) were obtained as exposure variables. We applied linear mixed-effect models to evaluate the effects of O_x and O_x^wton systolic BP (SBP), diastolic BP (DBP), mean arterial pressure (MAP) and pulse pressure (PP).

Totally, 160 pairs of valid BP values were obtained. The 24-h mean levels of O_x and O_x^wt were 64.38 μg/m³ and 110.28 μg/m³, respectively. Overall, both O_x and O_x^wt were significantly linked with SBP, DBP and MAP at most lag periods, whereas non-significant with PP. A 10-μg/m³ increase in O_x^wt at lag 0-24 h was linked to increases of 2.43 mmHg (95% CI: 0.96, 3.91) in SBP, 2.31 mmHg (95% CI: 1.37, 3.26) in DBP and 2.35 mmHg (95% CI: 1.35, 3.36) in MAP, while the corresponding effect estimates for O_x were 1.51 mmHg (95%CI: 0.60, 2.43), 1.43 mmHg (95% CI: 0.85, 2.02) and 1.46 mmHg (95%CI: 0.83, 2.09). In two-pollutant models, our results were almost unchanged after controlling for simultaneous exposure to other pollutants. The effects were more pronounced among males and those with physical activity.

The findings provide first-hand evidence that short-term exposure to O_x and O_x^wt was associated with BP increases in young adults.