Association between air pollutants and cardiovascular disease mortality in Wuhan, China

We examined the associations of daily mean concentrations of ambient air pollutants (particulate matter (PM10), sulfur dioxide (SO₂), nitric oxide (NO₂)) and daily cardiovascular diseases (CVD) mortality in Wuhan, China using a case-crossover design to analyze four years of data (2006–2009) collected from the Hubei Provincial Center for Disease Control and Prevention and the Wuhan Environmental Protection Bureau. From 2006 to 2009, daily average concentrations of PM₁₀, SO₂and NO₂were 115.60 μg/m³, 53.21 μg/m³and 53.08 μg/m³, respectively. After adjusting for temperature and relative humidity, a 10 μg/m³increase in SO₂and NO₂over a 24-h period was associated with CVD mortality relative risk (R.R.) of 1.010 (95% CI: 1.000, 1.020) for SO₂and 1.019 (95% CI: 1.005, 1.033) for NO₂, but there was no significant association between increases in PM10 and mortality. Subgroup analysis on by gender showed a significant association of 1.026 (95% CI: 1.007, 1.045) between NO₂and CVD among males, while no significant statistical effect was shown among females. Subgroup analysis by age showed that for those older than 65 years, every 10 μg/m³increase in NO₂was associated with a 1.6% (95% CI: 0.1%, 3.1%) increase in CVD mortality. Subgroup analysis on different types of CVD showed that every 10 μg/m³increase in PM₁₀and SO₂were significantly associated with an approximately 1.012 (95% CI: 1.002, 1.022) and 1.021 (95% CI: 1.002, 1.040) increase, respectively, in ischemic heart disease (ICH) mortality. In conclusion, exposure to NO₂is significantly associated with CVD mortality. Larger, multi-center studies in Chinese cities are being currently conducted to validate these findings.