Heavy smog in northern China caused the closure of several highways and hundreds of flights Sunday.
The air pollution started Friday and is expected to last until Thursday, but is expected to ease up by Monday, Reuters reported.
In Beijing, 126 flights were canceled at the city’s main airport and all bus service to the surrounding cities was suspended, according to state news agency Xinhua.
In Tianjin, not too far away from Beijing, the smog was not as bad but visibility was much worse with conditions not expected to improve in the near future, causing the cancellation of more than 300 flights at Tianjin airport, the city government said.
This isn’t the first time northern China has been hit by smog.
In mid-December, Beijing was hit with hazardous smog that caused officials to issue a five-day “red alert” where schools were shut down, residents were told to stay inside, and drivers were told to stay off the roads, the Guardian reported.
Authorities ordered the closure of hundreds of factories and issued restrictions for drivers in order to cut emissions as a result.
For the current round of smog, 24 Chinese cities have issued red alerts while 21 cities have issued orange alerts, including Beijing and Tianjin.
China started a “war on pollution” in 2014 to combat concerns that the pollution was impeding future development, but the country has found little success in managing the problem.