受不利气象条件影响，北京空气质量达到重度污染水平

Core Viewpoint - Beijing is experiencing severe air pollution, with the air quality index reaching 209, indicating heavy pollution levels primarily due to PM2.5 emissions [1] Group 1: Air Quality Data - As of November 5, at 18:00, the air quality index in Beijing was recorded at 209, categorizing it as level five heavy pollution, with PM2.5 as the main pollutant [1] - The air quality deteriorated throughout the day, moving from moderate pollution at noon to heavy pollution by 17:00 [1] - Nighttime conditions are expected to remain poor, with the air quality index projected to range between 190-210, indicating moderate to heavy pollution levels [1] Group 2: Future Projections - On November 6, the air quality index is anticipated to be between 135-155, indicating light pollution levels due to the influence of northeastern high pressure [1] - By November 7, air quality is expected to improve to level two, indicating good conditions [1]