The Clean Development Mechanism’s (CDM) contribution to sustainable development in host countries has come under criticism in recent years. Yet, there are no detailed country-wide estimates of air quality cobenefits from CDM projects. In this paper, we estimate the SO2, PM2.5, and NOx cobenefit rates (tonnes per kt CO2eq reduced) of 11 CDM project types for seven regions in China, using detailed activity data from Project Design Documents and emissions factors calculated from the GAINS-Asia model database. We forecast the CO2eq reductions by CDM projects to 2012 and their associated contributions to air pollution reductions, and avoided health and agricultural impacts. We expect CDM projects to yield notable SO2 reductions in the coming years (1094 kt in 2010), with more modest reductions of PM2.5 and NOx (79 and 270 kt in 2010, respectively). This suggests that the CDM could be making a nontrivial contribution to China’s SO2 reductions under the 11th Five-Year Plan. The monetized health and agricultural benefits from reduced PM and NOx amount to roughly 12 billion RMB per year in 2010, roughly one-third of the market value of the associated Certified Emission Reductions.