Associations of black carbon and PM2.5 with daily cardiovascular mortality in Beijing, China

Due to its twofold effects on climate change and air quality, black carbon (BC) is of wide concern in the atmospheric sciences. Considerable uncertainty exists as to the health effects of atmospheric BC for the limited epidemiological and toxicological studies. As combustion-derived BC is one important component of PM2.5 (particles with aerodynamic diameters less than 2.5 mu m), the question remains of whether or not BC may play an important role in PM2.5-related health risks. To quantitatively analyze the short-term health effects of BC and PM2.5, a confounder-adjusted semi-parametric generalized additive model (GAM) of a time series study was used to calculate the concentration-response relationship between BC and PM2.5 and daily cardiovascular disease (CVD) mortality from 2006 to 2011 in Beijing. During the study period, the mean daily concentrations of BC and PM2.5 were 6.8 mu g/m(3) and 75.9 mu g/m(3), respectively. The results showed that BC was significantly associated with CVD mortality, and an interquartile range (IQR) increase in BC (5.7 mu g/m(3)) and PM2.5 (64. 5 mu g/m(3)) were associated with 2.70% (95% CI: 2.20, 3.21) and 4.06% (95% CI: 3.47, 4.65) increase in CVD mortality. The health risk associated with BC may less than that of PM2.5. When adjusted for nitrogen dioxide (NO2) and sulfur dioxide (SO2), the effects of BC remained statistically significant. It showed the relatively difference between BC and PM2.5 when it comes to the modification effects of age, gender and educational attainment. These findings provide valuable evidence to the rare studies of the concentration-response relationship of BC with human health in developing countries.