School classes will be suspended, government vehicles will be removed from roads and barbecue grills will be banned in two cities in east China where lingering smog has led to soaring pollution levels.

The National Meteorological Center on Wednesday renewed a yellow alert for fog and smog for the third consecutive day as smog continued to choke eastern and northern provinces and municipalities, including Shandong, Jiangsu, Zhejiang, Shanghai and Tianjin. The yellow alert is the third highest in a four-level alert system.

Pollution levels in the coastal city of Qingdao in Shandong Province worsened to "serious," prompting authorities to tighten supervision of heavy polluters including coal-fired boilers and construction sites while restricting the use of government vehicles.

Open-air burning of leaves and garbage as well as open-air barbecues will be banned, the government said in a statement, adding that outdoor school activities had been canceled since Tuesday.

The government of Nanjing, capital of Jiangsu Province, on Wednesday initiated a red-coded emergency response to air pollution, the highest response level, which includes heightened controls on industrial sources of pollutants.

The city's educational authorities on Wednesday evening also issued an urgent notice for all primary schools and kindergartens to suspend class.

Both Nanjing and Qingdao predicted the severe smog would continue, suggesting the measures are unlikely to be lifted soon.

China's central and eastern areas have been hit by a new round of foggy and smoggy weather since the start of December. The center predicted the weather would continue until Sunday. Endi