1f:T446,This paper finds that a 10-μg/m³ increase in airborne particulate matter [particulate matter smaller than 10 μm (PM₁₀)] reduces life expectancy by 0.64 years (95% confidence interval = 0.21-1.07). This estimate is derived from quasiexperimental variation in PM₁₀ generated by China's Huai River Policy, which provides free or heavily subsidized coal for indoor heating during the winter to cities north of the Huai River but not to those to the south. The findings are derived from a regression discontinuity design based on distance from the Huai River, and they are robust to using parametric and nonparametric estimation methods, different kernel types and bandwidth sizes, and adjustment for a rich set of demographic and behavioral covariates. Furthermore, the shorter lifespans are almost entirely caused by elevated rates of cardiorespiratory mortality, suggesting that PM₁₀ is the causal factor. The estimates imply that bringing all of China into compliance with its Class I standards for PM₁₀ would save 3.7 billion life-years.20:T541,Simultaneous measurements of atmospheric organic and elemental carbon (OC and EC) were taken during winter and summer seasons at 2003 in 14 cities in China. Daily PM 2.5 samples were analyzed for OC and EC by the Interagency Monitoring of Protected Visual Environments (IMPROVE) thermal/optical reflectance protocol. Average PM 2.5 OC concentrations in the 14 cities were 38.1 μ g m −3 and 13.8 μ g m −3 for winter and summer periods, and the corresponding EC were 9.9 μ g m −3 and 3.6 μ g m −3 , respectively. OC and EC concentrations had summer minima and winter maxima in all the cities. Carbonaceous matter (CM), the sum of organic matter (OM = 1.6 × OC) and EC, contributed 44.2% to PM 2.5 in winter and 38.8% in summer. OC was correlated with EC ( R 2 : 0.56–0.99) in winter, but correlation coefficients were lower in summer ( R 2 : 0.003–0.90). Using OC/EC enrichment factors, the primary OC, secondary OC and EC accounted for 47.5%, 31.7% and 20.8%, respectively, of total carbon in Chinese urban environments. More than two thirds of China's urban carbon is derived from directly emitted particles. Average OC/EC ratios ranged from 2.0 to 4.7 among 14 cities during winter and from 2.1 to 5.9 during summer. OC/EC ratios in this study were consistent with a possible cooling effect of carbonaceous aerosols over China.21:T812,

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