Comment: 35 pages, 5 tables, 8 figures in the main text, with supplementary appendix after referencesThis paper evaluates the impact of a mandatory shutdown policy of small-capacity coal power plants during China's $11^{th}$ 5-Year Plan period (2006--2010) on under-5 mortality. We collect capacity and location information on 2181 coal power plants that operated during 2000--2010 and compile a unique data set that combines coal power plants, county-level under-5 mortality and socioeconomic variables, high spatial resolution data of PM$_{2.5}$ and SO$_2$ and meteorological conditions. We model the impacts of air pollution on under-5 mortality using the IV-Lasso method, with distance-weighted sums of retired capacity and high-altitude wind status as instrumental variable candidates for air pollution. Our estimates imply that the phase-out policy saved around 46,000 lives during the $11^{th}$ 5-Year Plan period. We also find heterogeneity in the policy effects across regions. (\textit{JEL} I10, I18, P25, P28, Q52, Q53, Q58)