Air pollution and life expectancy in China and beyond

In PNAS, Chen et al. (1) present findings that implicate long-term exposure to air pollution as contributing to enormous loss of life expectancy (LE) in China. These results are based on a clever quasiexperimental, regression discontinuity design exploiting a Chinese policy that provided free coal for heating in cities north of the Huai River, but not in the south. A spatial discontinuity for particulate matter air pollution (PM), presumably from coal combustion, was observed. A spatial discontinuity of reduced LE of 5+ y was also observed. If true, these results suggest enormous health costs associated with air pollution in China and have important environmental, economic, and public health policy implications. However, are the results plausible? Are they coherent with other epidemiological studies?