Abstract:
Background Short-term exposure to air pollutants has been associated with elevated blood pressure. However, few studies have examined the relationship between particulate matter, blood pressure variability (BPV), and circadian rhythms. Objective To investigate the effects of air pollutant levels on BPV and blood pressure circadian rhythm in patients with essential
hypertension.Methods Patients admitted to the Department of Cardiology, the First Medical Center of PLA General Hospital from January 2019 to January 2022 and diagnosed with essential hypertension were included. BPV indicators and pollutant data, including particulate matter 2.5 (PM2.5) and particulate matter 10 (PM10), were collected. Standard deviation (SD) and coefficient of variation (CV) were used to evaluate the ambulatory BPV. A distributed lag model with median regression was constructed to assess lag effects and associations between air pollution components, BPV, and circadian rhythm. Results After adjusting for potential
confounders such as age, sex, and holidays, for every 10-μg/m³ increase in PM2.5, the maximum lag effect on daytime systolic blood pressure (dSBP) SD and dSBP CV was observed at lag 2, with increments of 1.42 (95% CI: 0.67 - 2.17) mmHg and 0.93 (95% CI: 0.34 - 1.53)%, respectively. For every 10- μg/m³ increase in PM2.5, the maximum lag effect on daytime diastolic blood pressure (dDBP) SD was observed at lag 0, with an increment of 2.27 (95% CI: 0.31 - 4.23) mmHg. For every 10-μg/m³ increase in PM10, the maximum lag effect on dDBP SD was observed at lag 0, with an increment of 2.09 (95% CI: 0.84 - 3.34) mmHg, while the maximum lag effect on nighttime diastolic blood pressure CV was observed at lag 2, with an increment of 1.68 (95% CI: 0.04 - 3.29) %. PM2.5 exerted the maximum cumulative effect on SBP dipping and DBP dipping at lag 06, with increments of 4.95 (95% CI: 0.82 - 9.10) mmHg and 5.16 (95% CI: 1.15 - 9.17) mmHg, respectively. The maximum cumulative lag effect of PM10 on SBP was observed at lag 05, with an increment of 18.13 (95% CI: 1.05 - 35.20) mmHg. The maximum cumulative lag effect of PM10 on SBP dipping and nDBP dipping was observed at lag 06, with increments of 6.94 (95% CI: 0.75 - 13.13) mmHg and 8.72 (95% CI: 0.08 - 17.37) mmHg, respectively.Conclusion A lag effect is observed between PM exposure and BPV. PM may be associated with non-dipping and reverse-dipping circadian rhythm patterns in patients with essential hypertension.