受外来沙尘传输影响，北京PM10可达到重度及以上污染水平

Core Viewpoint - A significant sandstorm event is affecting the northwestern regions of China and parts of Mongolia, leading to severe air quality issues, particularly in the Beijing-Tianjin-Hebei area [1] Group 1: Air Quality Impact - From February 20 to 21, a large-scale sandstorm caused PM10 levels in northwestern China to reach severe pollution levels, with some areas reporting PM10 concentrations of 2031 micrograms per cubic meter, indicating a level 6 severe pollution status [1] - In Beijing's Yanqing District, PM10 levels reached 594 micrograms per cubic meter, also classified as level 6 severe pollution, while the city's average PM10 concentration was 175 micrograms per cubic meter, indicating level 3 light pollution [1] Group 2: Forecast and Future Conditions - Predictions indicate that from the afternoon to night of February 21, PM10 levels in Beijing are expected to rise significantly, potentially exceeding 500 micrograms per cubic meter, which would classify as severe pollution [1] - Due to strong winds, the sandstorm is expected to move out of Beijing by the early morning of February 22, with air quality improving to levels 1-2, indicating good quality [1]