Synergistic air pollution and CO2 emission reduction in China's iron and steel industry based on real-time monitoring data.

As the world's largest producer of crude steel, China's iron and steel industry (ISI) is one of the major sources of both air pollutant and carbon dioxide (CO2) emissions in the country. To better track emission patterns and assess the synergistic reduction potential under various policies during the 14th Five-Year Plan period, a high-frequency, smokestack-level and national emission database was developed that covers both air pollutants (i.e., particulate matter (PM), sulfur dioxide (SO2) and nitrogen oxides (NOx)) and CO2 emissions in the ISI from 2021 to 2023. The results demonstrated a consistent downward trend in air pollutant concentrations, with average annual reductions of 17.36 %, 12.96 %, 11.38 % and 0.02 % for PM, SO2, NOx and CO2, respectively. Notable reductions in air pollutant and CO2 emissions were also observed, indicating the effectiveness of existing control measures. Moreover, scenario analysis indicated that ultra-low emission (ULE) compliance and carbon capture, utilization, and storage (CCUS) are the most effective methods for mitigating air pollutant and CO2 emissions, respectively, whereas structural adjustment through increased adoption of electric arc furnaces (EAF) provided the greatest synergistic emission reductions. These findings provide critical insights for designing synergistic control strategies targeting the ISI in China and other developing economies (e.g., India), aiming to address air pollution and climate change.