Associations of long-term exposure to air pollution with blood pressure and homocysteine among adults in Beijing, China: A cross-sectional study

Abstract Background Studies on the hypertensive effect of long-term exposure to air pollution are mixed, and sparse evidence exists regarding its effects on homocysteine (Hcy), another crucial risk factor for cardiovascular disease (CVD). Methods We collected data from 23,570 participants aged 18-74 years at baseline (years 2017-2018) from a community-based cohort in China. A linear combination of concentrations from monitoring stations at the participants’ home and work addresses, weighted by the time, was used to estimate two-year exposures to particulate matter with fine particles≤2.5 μm (PM2.5), aerodynamic diameter≤10 μm (PM10), nitrogen dioxide (NO2) and sulfur dioxide (SO2). Generalized linear regressions and logistic regressions were conducted to examine the associations between air pollution and systolic blood pressure (SBP), diastolic blood pressure (DBP), Hcy, hypertension and co-occurrence of hypertension and hyperhomocysteinemia (HHcy). Results The results showed that each interquartile range (IQR) increase in PM2.5 (16.1 μg /m3), PM10 (19.3 μg /m3) and SO2 (3.9 μg /m3) was significantly associated with SBP (changes: 0.64-1.86 mmHg), DBP (changes: 0.35-0.70 mmHg) and Hcy (changes: 0.77-1.04 μ mol/L) in the fully adjusted model. These air pollutants were also statistically associated with the prevalence of co-occurrence of hypertension and HHcy (ORs: 1.22-1.32), which were stronger than associations with the prevalence of hypertension (ORs: 1.09-1.19). The hypertensive effects of exposure to PM2.5, PM10 and SO2 were more pronounced among elder participants, obese participants, those with established CVD or a high 10-year CVD risk and those with a family history of hypertension. However, interaction analyses of Hcy showed different patterns. Additionally, moderate level of physical activity and active travel mode benefited individuals in resisting the health impacts of air pollution on both blood pressure (BP) and Hcy. Conclusions Our study supports a positive relationship between air pollution and BP and Hcy among adults in Beijing, and close attention to vulnerable populations and healthy lifestyles could effectively benefit further cardiovascular health.