BEIJING, April 3 (Xinhua) -- Beijing upgraded its alert for air pollution to orange Monday afternoon, the second highest warning.
The smog, affecting Beijing and adjacent Tianjin and Hebei, is forecast to last until Friday. Beijing had issued the yellow alert early Monday morning, but the density of hazardous fine particle matter PM2.5 continued to grow.
"The wind is not strong enough and the air quality is likely to get worse," said the Beijing Municipal Environmental Protection Bureau.
The Beijing Municipal Environmental Monitoring Center forecasts that PM2.5 readings will be between 200 and 220 micrograms per cubic meter Tuesday.
Under the orange alert, outdoor paint and construction is suspended; trucks carrying garbage, sand and soil are taken off roads; and outdoor activities in kindergartens, middle schools and primary schools are stopped.
Beijing has a four-tier color alert system for pollution, with red being the highest, followed by orange, yellow and blue.