BEIJING -?China's environmental authority forecast heavy air pollution from Wednesday through to Sunday in northern China.

Smog will linger in Beijing, Tianjin and a number of cities in the provinces of Hebei, Shandong, Shanxi, Henan, Jiangsu, Anhui and Shaanxi, according to a Ministry of Environmental Protection report on Wednesday.

Beijing has issued an orange alert, the second highest in the four-tier warning system, for air pollution. The alert will be effective from midnight Thursday.

The ministry said it has sent inspection teams to relevant localities to make sure proper response measures are taken.