A citizen rides a bicycle in Beijing.
Severe smog in northern China worsened late Monday, disrupting the lives of hundreds of millions of people.
Zhengzhou, capital of central China's Henan Province, ordered all primary schools to cancel classes for the next two days. Liaoning Province saw its most severe smog in seven years, with poor visibility closing 18 expressways.
Tianjin airport suspended services from Sunday evening to Monday noon. As of 5 p.m. on Monday, a total of 29 flights had been delayed and 350 canceled.
All expressways in the municipality were closed. Extra public transportation was laid on as cars are running on odd-even plate restrictions until midnight Thursday.
Tianjin Municipal Education Bureau issued an emergency notice on Monday night, ordering schools and kindergartens to suspend classes in the following two days.
Beijing also increased its public transport and implemented the same odd-even number plate rule.
The Beijing municipal environmental protection bureau has introduced a spate of pollution reduction measures, including vehicle restrictions, to help cut PM2.5 pollutant emissions by over 20 percent.
The meteorological station in east China's Shandong Province on Monday issued its first red alert for smog in this winter. It also issued another red alert for heavy fog.
Over 100 toll gates on four expressways in Shandong were closed and some flights at the provincial capital airport were delayed.
A total of 1,767 enterprises have halted production and workers on 2,036 construction sites across the province stopped working on Monday, according to a statement on the official website of the provincial environmental protection department.
All kindergartens, primary schools and middle schools in Xi'an, capital of northwest China's Shaanxi Province, were closed on Monday. Teachers offered online classes via chatting apps such as Wechat and QQ, while some schools offering live classes to students at home.
Liu Junbo, head of Xi'an No. 26 Middle School, said some teachers had tried real-time tutoring via live broadcasts and others kept in touch with students through Wechat, the Internet and phone.
The smog descended over the weekend and is forecast to clear by Thursday. Over 20 cities have issued red alerts.
On Monday, the PM2.5 reading in many cities in northern China, mainly in Hebei and Henan, exceeded 500 micrograms per cubic meter. In Shijiazhuang, capital of Hebei, the reading exceeded 1,000 micrograms per cubic meter at 1 p.m. Monday.