Acute effect of air pollutants’ peak-hour concentrations on ischemic stroke hospital admissions among hypertension patients in Beijing, China, from 2014 to 2018

Air pollutants’ effect on ischemic stroke (IS) has been widely reported. But the effect of high-level concentrations during people’s outdoor periods among hypertension patients was unknown. Peak-hour concentrations were defined considering air pollutants’ high concentrations as well as people’s outdoor periods. We conducted a time-series study and used the generalized additive model to analyze peak-hour concentrations’ acute effect. A total of 315,499 IS patients comorbid with hypertension were admitted to secondary and above hospitals in Beijing from 2014 to 2018. A 10 µg/m³ (CO: 1 mg/m³) increase of the peak-hour concentrations was positively associated with IS hospital admissions among hypertension patients. The maximum effect sizes were as follows: for PM₂.₅, 0.17% (95% confidence interval [CI]: 0.10–0.24%) at Lag0 and 0.22% (95% CI: 0.12–0.33%) at Lag0–5; for PM₁₀, 0.09% (95% CI: 0.05–0.13%) at Lag5 and 0.17% (95% CI: 0.09–0.26%) at Lag0–5; for SO₂, 0.87% (95% CI: 0.46–1.29%) at Lag5; for NO₂, 0.83% (95% CI: 0.62–1.04%) at Lag0 and 0.86% (95% CI: 0.59–1.13%) at Lag0–1; for CO 1.23% (95% CI: 0.66–1.80%) at Lag0 and 1.33% (95% CI: 0.33–2.35%) at Lag0–5; for O₃ 0.23% (95% CI: 0.12–0.35%) at Lag0 and 0.20% (95% CI: 0.05–0.34%) at Lag0–1. The effect sizes of PM₂.₅, NO₂, and O₃ remained significant after adjusting daily mean. Larger effect sizes were observed for PM₂.₅ and PM₁₀ in cool season and for O₃ in warm season. As significant exposure indicators of air pollution, peak-hour concentrations exposure increased the risk of IS hospital admissions among hypertension patients and it is worthy of consideration in relative environmental standard. It is suggested for hypertension patients to avoid outdoor activity during peak hours. More relevant searches are required to further illustrate air pollutant’s effect on chronic disease population.