Affected by regional adverse meteorological conditions, PM2.5 in Beijing reached mild to moderate pollution on the 25th

On the night of October 24th to the morning of October 25th, the Beijing Municipal Ecological Environment Monitoring Center reported that the city and nearby areas have entered a low-pressure convergence zone. Wind speeds have been consistently below 1 m/s, and relative humidity is nearly saturated. This has led to significant temperature inversions, resulting in poor air dispersion conditions. Consequently, pollution levels in Beijing and its surroundings have quickly escalated, predominantly reaching a level of mild pollution (Grade 3), with some urban areas experiencing moderate pollution levels (Grade 3-4).

Due to prevailing southern and eastern winds near the surface, there has been noteworthy pollution transport. As a result, the concentration of PM2.5 in Beijing has rapidly increased, reaching mild pollution levels on the morning of the 25th, with some monitoring stations recording moderate pollution. By 11 AM, PM2.5 levels surged to 127 micrograms per cubic meter, categorized as Grade 4 moderate pollution.

Forecast analyses indicated that from the night of the 25th to the morning of the 26th, the region would continue to experience closed low pressure, high humidity, and strong temperature inversions, creating particularly unfavorable meteorological conditions. As pollution accumulation and transmission continue, it is expected that air quality will further deteriorate, potentially reaching moderate pollution levels (Grade 4) during the night, with some periods and locations possibly reaching levels classified as heavy pollution (Grade 4-5).

However, by the afternoon of the 26th, cooler temperatures and diminishing north winds are anticipated to improve dispersion conditions gradually. Overall, air quality is expected to remain at mild to moderate pollution levels (Grade 3-4). As the night progresses, a transition to a northwest cold high-pressure system will occur, leading to a more noticeable drop in temperature and an increase in north winds. This change is expected to significantly enhance dispersion conditions, with air quality likely improving to a good level (Grade 2) on the 27th, and reaching excellent levels (Grade 1) by the same day under the influence of persistent cold high pressure and strong north winds.