Air pollutants and outpatient visits for cardiovascular disease in a severe haze-fog city: Shijiazhuang, China

BACKGROUND: Many studies have reported the impact of air pollution on cardiovascular disease (CVD), but few of these studies were conducted in severe haze-fog areas. The present study focuses on the impact of different air pollutant concentrations on daily CVD outpatient visits in a severe haze-fog city. METHODS: Data regarding daily air pollutants and outpatient visits for CVD in 2013 were collected, and the association between six pollutants and CVD outpatient visits was explored using the least squares mean (LSmeans) and logistic regression. Adjustments were made for days of the week, months, air temperature and relative humidity. RESULTS: The daily CVD outpatient visits for particulate matter (PM(10) and PM(2.5)), sulphur dioxide (SO(2)), nitrogen dioxide (NO(2)), carbon monoxide (CO), and ozone (O(3)) in the 90th-quantile group were increased by 30.01, 29.42, 17.68, 14.98, 29.34%, and − 19.87%, respectively, compared to those in the <10th-quantile group. Odds ratios (ORs) and 95% confidence intervals (CIs) for the increase in daily CVD outpatient visits in PM(10) 300- and 500-μg/m(3), PM(2.5) 100- and 300-μg/m(3) and CO 3-mg/m(3) groups were 2.538 (1.070–6.020), 7.781 (1.681–36.024), 3.298 (1.559–6.976), 8.72 (1.523–49.934), and 5.808 (1.016–33.217), respectively, and their corresponding attributable risk percentages (AR%) were 60.6, 87.15, 69.68, 88.53 and 82.78%, respectively. The strongest associations for PM(10), PM(2.5) and CO were found only in lag 0 and lag 1. The ORs for the increase in CVD outpatient visits per increase in different units of the six pollutants were also analysed. CONCLUSIONS: All five air pollutants except O(3) were positively associated with the increase in daily CVD outpatient visits in lag 0. The high concentrations of PM(10), PM(2.5) and CO heightened not only the percentage but also the risk of increased daily CVD outpatient visits. PM(10), PM(2.5) and CO may be the main factors of CVD outpatient visits.