In addition to regular controls on production and vehicle use, some cities have tightened restrictions to reduce emissions of airborne pollutants.

In 10 cities in Shanxi province, including the provincial capital Taiyuan, all plants in mining, sand excavation, processing of stones and asphalt mixing industries were required to suspend production from Dec 1 to 4.

In Langfang, Hebei province, all casting factories and cement-making plants (except those providing heating services for residential communities) are required to suspend production in December.