Health and climate impacts of policy-driven changes in open crop straw burning during China's summer harvest

Abstract

Open crop straw burning (OCSB) substantially affects the air quality in China, prompting control measures and straw-burning bans. However, long-term policy-driven impacts on air quality, public health, and climate at the national scale have received limited quantitative assessment within a unified framework. Here, we combine a localized OCSB emission inventory with paired WRF-Chem simulations (with and without OCSB) for June in 2003, 2008, 2013, 2018, and 2021 to quantify these impacts. The OCSB-induced nationwide mean PM_2.5 reached 2.82 µg m⁻³ in 2013, decreased by ∼79.4% to 0.58 µg m⁻³ in 2018, and slightly rebounded in 2021. The population-weighted PM_2.5 exposure attributable to OCSB decreased by ∼78.1% (from 10.48 µg m⁻³ in 2013 to 2.29 µg m⁻³ in 2021), and the non-accidental premature deaths declined by ∼77.6% (from 1756; 95% confidence interval, 95% CI: 1200–2231) in 2013 to 393 (95% CI: 268–500) in 2021. The reduced OCSB emissions weakened the aerosol-induced shortwave dimming and surface cooling, indicating a diminishing compensating climate effect. Nationally, the OCSB-attributable surface shortwave net radiation (SWNET) increased from −0.64 to −0.25 W m⁻² between 2013 and 2021, and the associated 2 m temperature (T₂) impacts weakened from −0.0056 °C to −0.0033 °C, especially over the North China Plain. Overall, our results suggest that recent reductions in OCSB emissions during the summer harvest are associated with substantial co-benefits for air quality, public health, and climate, providing national-scale evidence for refining straw-burning bans and air-pollution control strategies.