Revealing air quality impacts of the clean heating campaign in northern China

To mitigate air pollution caused by bulk coal burning for heating in northern China during winter, the Chinese government initiated a clean heating campaign in Beijing and the surrounding region starting in 2017. The impact of this historic campaign remained unclear at a fine spatial and temporal resolution. Based on the annually updated high spatial resolution surveyed coal substitution data, this study coupled the multi-period difference-in-differences (DID) model with the two-stage DID model and found that bulk coal substitution would have led to a spatially and temporally averaged reduction by 4.0 μg/m3 in wintertime PM2.5 concentration over Beijing and the surrounding region. Furthermore, taking advantage of the spatially disaggregated data, spillover effects associated with air pollution transportation were further quantified. Considering these effects, the estimated air quality benefit would increase to 8.2 μg/m3. Additionally, these benefits exhibit sustainability, with the fourth year post-implementation 3.6 times greater than the initial year, suggesting cumulative effects of the policy. On average, every 1kt of bulk coal substitution resulted to 0.3 μg/m3 PM2.5 reduction at a 0.1° × 0.1° grid. These findings, validated through extensive robustness testing, underscore the effectiveness and sustainability of the clean heating campaign and would offer valuable insights for relevant policy formulation in China or other developing countries.