The impact of short-term exposure to nitrogen dioxide on endothelial function in elders: a cross-sectional study

Background Nitrogen dioxide (NO2) is linked to the escalation of cardiovascular disease (CVD) and mortality rates. As the underlying mechanisms of the adverse effects of NO2 on vascular endothelial function are not well understood, we explored the effects of NO2 short-term exposure on the flow-mediated dilation (FMD), an early marker associated with vascular endothelial dysfunction (VED). Purpose We aimed to evaluate the association between short-term NO₂ exposure and endothelial function, as measured by FMD, in elderly individuals. Additionally, it sought to identify vulnerable subgroups and assess the delayed effects of NO₂ exposure on vascular endothelial dysfunction (VED), defined as FMD < 6.0%. Methods We performed a cross-sectional population-based study from 2020 to 2022. One individual who underwent FMD assessment were extracted. Exposure data was obtained from the Tracking Air Pollution in China (TAP) portal. The effects of NO2 on FMD and VED were explored by generalized additive models withdistributed lag nonlinear model (DLNM), over a lag period of 0 to 10 days (Lag0-Lag10). Subgroup analyses were conducted to identify populations more susceptible to NO₂ exposure. Results A total of 812 elderly adults were employed in the final analysis. NO2 were significantly associated with a decrease in FMD with a lag of 1, 5 and 6 days, while increased the risk of VED just on lag 5 day. For the Cumulative effect analysis, we also observed significant associations between NO2 range from 35 to 85 μg/m3 and FMD. Subgroup analysis showed that participants who are male, non-smokers, non-drinkers, and have no history of hyperlipidemia, CVD and coronary artery disease (CAD) were more vulnerable to short-term NO2 exposure. Conclusions Short-term exposure to NO2 was observed to exert a negative influence on the endothelium function of the elderly. This finding supports the role of short-term NO2 exposure in vascular endothelial injury and enriches the knowledge of FMD as a new indicator for evaluating vascular endothelial injury. Percentage change of FMD and risk of VED