Air quality in seven districts of Beijing reached the severe pollution level on Monday afternoon, with PM2.5 particulate matter peaking at 182 micrograms per cubic meter, according to the municipal environment monitoring center. 

The seven districts — mainly in central and southeastern Beijing — include Xicheng, Dongcheng, Chaoyang, Shunyi, Daxing, Tongzhou and Pinggu, the center was quoted as saying. 

Humidity is high, which is not good for the diffusion of contaminants, the center said. It predicted that air quality would be better by Tuesday morning. 

Beijing reported 206 good air days in the first nine months of the year, an increase of nine days year-on-year, according to the city's ecology and environment bureau. 

The average monthly reading for PM2.5 in September fell to 18 micrograms per cubic meter, and the city set an air-quality record for its cumulative PM2.5, a primary gauge of air pollution. It fell to an average of 33 micrograms per cubic meter in the first three quarters of the year.

PM2.5, which refers to airborne particles smaller than 2.5 micrometers in diameter, poses serious health risks.