Characteristics and Causes of PM2.5 Changes in the Fenwei Plain from 2013 to 2020
To combat severe air pollution, China has implemented a series of air pollution control action plans since 2013, effectively alleviating PM2.5 pollution. However, PM2.5 concentrations in most cities within the Fenwei Plain still exceed national standards. This study systematically evaluates PM2.5 concentration changes across two policy phases (2013–2020) using the Community Multiscale Air Quality (CMAQ) model, quantifying contributions of meteorology and emissions, and analyzing sectoral source changes. Results show that annual average PM2.5 concentration declined cumulatively by 19% during 2013–2020. In the first phase (2013–2017), regional PM2.5 decreased by 3% annually, with most improvement in winter; however, due to unfavorable meteorology, concentrations increased in Xi'an and Xianyang. In the second phase (2017–2020), PM2.5 declined by an additional 16%, with more effective control measures, particularly in spring and autumn. Emission reductions dominated in both phases, with stronger effects in the second phase (−8 μg·m−3), significantly outweighing adverse meteorological contributions (+3.5 μg·m−3). Nevertheless, many cities still face challenges from unfavorable meteorology, highlighting the need for future policies to account for meteorological influences. Emissions from industrial, energy, and agricultural sources decreased significantly across both phases. However, during winter heating periods, residential emissions emerged as a source equal in importance to industrial emissions, becoming a key target for future emission controls.