Coal-fired　heating　in　winter　is　a　primary　source　of　air　pollution　in　many　countries.　In　northern　China,　the　use　of　scattered　coal　for　winter　heating　has　led　to　severe　environmental　issues.　In　this　study,　we　use　a　quasi-natural　experiment　in　Shandong　Province,　China,　to　investigate　the　effectiveness　of　a　cleaner　heating　transition　policy.　Specifically,　we　use　a　difference-in-differences　approach　to　identify　the　effects　of　the　cleaner　heating　transition　policy　on　air　pollution　using　high-resolution　hourly　data.　Our　findings　indicate　that　implementation　of　the　policy　could　effectively　reduce　air　pollution　by　decreasing　a　PM2.5　by　7.32%,　PM10　by　2.62%,　SO2　by　3.98%,　and　NO2　by　4.67%.　In　addition,　we　used　event　study　and　a　series　of　robustness　checks　to　further　support　our　findings.　Notably,　our　findings　indicate　that　implementation　of　the　policy　includes　a　spatial　spillover　effect,　which　differs　according　to　the　level　of　compulsory　implementation　and　the　distance　to　a　city　centre.　Overall,　our　findings　can　help　promote　the　application　of　a　cleaner　transitioning　policy　for　the　entire　country　and　offer　guidance　for　further　policy　development　regarding　the　effective　reduction　of　winter　air　pollution　in　the　developing　world.