Study on the association between ambient air pollution and daily cardiovascular death in Hefei, China

Cardiovascular disease has always been the most serious public health problem in China. Although many studies have found that the risk of death caused by cardiovascular disease is related to air pollutants, the existing results are still inconsistent. The aim of this study was to investigate the effects of air pollutants on the risk of daily cardiovascular deaths in Hefei, China. Daily data on cardiovascular deaths, daily air pollutants, and meteorological factors from 2007 to 2016 were collected in this study. A time-series study design using a distributed lag nonlinear model was employed to evaluate the association between air pollutants and cardiovascular deaths. First, a single air pollutant model was established based on the minimum value of Akaike information criterion (AIC), and the single day lag effects and multi-day lag effects were discussed separately. Then, two-pollutant models were fitted. Subgroup analyses were conducted by gender (male and female), age (< 65 age and ≥ 65 age), and disease type (ischemic heart disease and cerebral vascular disease). There were 34,500 cases of cardiovascular deaths during the period 2007–2016, and the average concentrations of air pollutants (PM₁₀, SO₂, NO₂, PM₂.₅, CO, O₃) were 106.11, 20.34, 30.49, 72.59, 958.7, and 67.88 μg/m³, respectively. An increase of interquartile range (IQR) in PM₁₀, SO₂, NO₂, PM₂.₅, CO, and O₃ were associated with an increase of 4.34% (95%CI 1.54~7.23%) at lag 0–6, 5.79% (95%CI 2.43~9.27%) at lag 0–5, 4.47% (95%CI 1.64~7.37%) at lag 0–5, 3.14% (95%CI 0.03~6.36%) at lag 0–4, 3.11% (95%CI 0.21~6.10%) at lag 0–3, and 8.17% (95%CI 1.89~14.84%) at lag 0–5 in cardiovascular deaths, respectively. Females, older group (≥ 65 years) and deaths from cerebral vascular disease were more vulnerable to air pollution than males, younger individuals (< 65 years) and deaths from ischemic heart disease. Our results suggest that air pollution increased the risk of cardiovascular deaths in Hefei. These findings can provide evidence for effective air quality interventions in Hefei.