North China's Hebei Province has been shrouded in heavy air pollution since Monday, with the average daily air quality index (AQI) in some cities soaring.
Shijiazhuang, the capital city, continued to be enveloped by smog Tuesday, with its AQI at 500 at around 11 a.m. An AQI of over 300 indicates serious pollution.
Other Hebei cities including Baoding, Hengshui, Xingtai, Handan and Dingzhou also suffered from heavy air pollution with the AQI above 200.
The local environmental emergency and heavy pollution warning center attributed the serious air pollution to dust and PM2.5, airborne particles smaller than 2.5 micrometers in diameter.
The air pollution is likely to persist in south-central and eastern regions of the province until next Monday, before a cold front improves the air quality.
On Nov. 22, Hebei issued an orange alert for heavy air pollution in 10 cities and about 35,000 enterprises involving gas emission took staggered production.
China has a four-tier color-coded warning system for severe weather, with red most serious, followed by orange, yellow and blue.
Hebei, Beijing's neighbor and home to several of the country's top 10 most polluted cities, is at the forefront of China's fight against air pollution.