Does the Coal-to-Gas Policy Reduce Air Pollution? Evidence from the Five-Phase Pilot Program in China

Wintertime ambient air quality in northern China has improved markedly over the past decade, yet the role of the household sector in this improvement remains unclear. This study evaluates the impact of an energy transition policy targeting the household sector—namely, the coal-to-gas policy—on wintertime air quality in northern China. Using balanced panel data covering the period from 2015 to 2023, we adopt a staggered difference-in-differences approach as our baseline empirical strategy to examine the policy’s effects across five implementation phases, and report results using heterogeneity-robust estimators to address the “forbidden comparison” issue. The results show that the policy significantly improved the Air Quality Index (8.3–12.5 %) and reduced concentrations of PM2.5 (9.8–15.6 %,), PM₁₀ (8.2–12.7 %), SO₂ (26.4–33.6 %), and NO₂ (7.4–10.5 %), though this was accompanied by an increase in ozone concentrations (8.3–12.9 %). To explore channels, we analyze household-level data from both urban and rural areas. We find that the policy has significantly increased urban clean energy infrastructure, promoted the expansion of centralized heating systems, and raised the likelihood of households adopting clean energy in rural areas.