Reuters reports that China's smog has practically shut down Heilongjiang province in the northeast, home to 11 million people, in the country’s first major air pollution crisis of the fall. Schools were forced to suspend classes and airports were shut down due to the lack of visibility that was only half the length of a football field. The official Xinhua news agency blamed the emergency on residents who turned on their heat for the first day of cold weather.

Reuters also reports that an index measuring PM2.5 (particulate matter with a diameter of 2.5 micrometers) reached a reading of 1,000 in some parts of Harbin, the capital of Heilonjiang province. Any level above 300 is considered hazardous. As the region enters its high smog season, The Washington Post reports that the current particulate levels are a record 40 times higher than the international safety standard.

Along with the closure of schools and airports, traffic was suspended as well as multiple bus routes, essentially immobilizing the area. Visibility was down to just 10 meters and is predicted to continue so for the next 24 hours. The winter season typically brings the worst air pollution to northern China, thanks to the weather in combination with burning coal for home heating.

Harbin’s heating system started running on Sunday, and the smog hit on Monday. Wu Kai, a housewife and mother of a baby boy, told The Washington Post in an interview from Harbin, “I couldn’t see anything outside the window of my apartment and I thought it was snowing. Then I realized it wasn’t snow. I have not seen the sun in a long time.”