Does psychosocial stress modify the association of fine particulate matter and ozone with cardiovascular health indicators?

Fine particulate matter (PM_2.5) and ozone (O₃) air pollution can cause abnormal changes in blood pressure (BP), blood glucose and lipids, which are important indicators for cardiovascular health. Psychosocial stress could be a potential effect modifier for adverse health effects of air pollution, but research evidence is scarce. A cross-sectional study with 373 elderly subjects was conducted in Beijing during 2018–2019. We collected psychosocial stress information on anxiety, perceived stress and depression, obtained daily environmental data, measured resting BP, blood glucose and lipids in study participants, and analyzed the associations of PM_2.5 or O₃ with cardiovascular health indicators and the modification effect by psychosocial stress. Results showed that PM_2.5 was significantly associated with increased systolic blood pressure (SBP), diastolic blood pressure (DBP), and pulse pressure (PP); and O₃ was significantly associated with elevated DBP, glycated hemoglobin (HbA1c) and total triglyceride (TG). In addition, the associations of PM_2.5 with TG, and O₃ with SBP and TG were higher in participants with high psychosocial stress, whereas the associations of O₃ with high-density lipoprotein cholesterol (HDL-C) were higher in participants with low psychosocial stress. For an interquartile range (IQR) (56.8 μg/m³) increase in PM_2.5 at 4-d moving average, TG increased by 21.43% (95% CI: 2.90, 43.29) in high perceived-stress group, and decreased by 20.05% (95% CI: −30.31, −8.28) in low perceived-stress group (p for interaction = 0.04). For an IQR (63.0 μg/m³) increase in O₃ at 2-d moving average, TG increased by 32.01% (95% CI: 7.65, 61.89) in high perceived-stress group, and increased by 7.95% (95% CI: −9.80, 29.20) only in low perceived-stress group (p for interaction = 0.04). For an IQR (64.0 μg/m³) increase in O₃ at 3-d moving average, HDL-C decreased by 4.55% (95% CI: −12.15, 3.72) in high perceived-stress group, and increased by 0.57% (95% CI: −6.99, 8.75) in low perceived-stress group (p for interaction=0.002). In conclusion, our results indicated that short-term exposures to PM_2.5 and O₃ were associated with significant changes in BP, blood glucose and lipids, and psychosocial stress may increase the susceptibility of the participants to the adverse cardiovascular effects of PM_2.5 and O₃.