SHANGHAI, Oct 8 (SMM) – China’s northern regions lifted the orange smog alerts for heavy air pollution which were activated before the National day holidays. Industrial plants have been ordered to curtail operation.

An orange alert is issued when the air quality index surpasses 200 for three consecutive days. Under Beijing's current air pollution warning system, yellow alert is the least severe, followed by orange and red.

Tangshan, China’s biggest steelmaking city, removed the orange alert from CST 8:00 October 4. Other cities in North China such as Beijing and Tianjin as well as provinces of Hebei, Shanxi, Shandong, Henan, Anhui and Jiangsu also lifted the alert in early October.