9月上半月，全国大部空气质量以优良为主

Core Viewpoint - The overall air quality in China during the first half of September 2023 is predominantly good, influenced by precipitation and cold air, with localized ozone pollution expected in some areas [1][2][3][4][5][6] Summary by Region Beijing-Tianjin-Hebei and Surrounding Areas - The air quality is mainly good, with slight pollution in some southern cities during specific periods due to temperature fluctuations and varying air flow [1][2] Yangtze River Delta - The air quality is generally good to lightly polluted, with localized areas experiencing light pollution due to high-pressure systems and precipitation [2] Fenwei Plain - The air quality remains predominantly good, with slight pollution in eastern areas, influenced by precipitation and temperature increases [3] Northeast Region - The air quality is mostly good, with potential light pollution in certain areas due to cold air and precipitation [4] South China - The air quality is primarily good, with some areas experiencing light pollution, particularly in central and northern regions [5] Southwest Region - The air quality is mainly good, with some cities experiencing light pollution due to temperature increases, while overall conditions are favorable [5] Northwest Region - The air quality is generally good, with localized light pollution and potential moderate pollution in southern Xinjiang due to dust storms [6]