Fire fighters take part in an emergency drill against winter chemical hazards and accidents in Wuhai, north China's Inner Mongolia Autonomous Region, Nov. 25, 2020. (Xinhua/Peng Yuan)

Aerial photo shows fire fighters taking part in an emergency drill against winter chemical hazards and accidents in Wuhai, north China's Inner Mongolia Autonomous Region, Nov. 25, 2020. (Xinhua/Peng Yuan)

Fire fighters take part in an emergency drill against winter chemical hazards and accidents in Wuhai, north China's Inner Mongolia Autonomous Region, Nov. 25, 2020. (Xinhua/Peng Yuan)

Fire fighters take part in an emergency drill against winter chemical hazards and accidents in Wuhai, north China's Inner Mongolia Autonomous Region, Nov. 25, 2020. (Xinhua/Peng Yuan)

Fire fighters take part in an emergency drill against winter chemical hazards and accidents in Wuhai, north China's Inner Mongolia Autonomous Region, Nov. 25, 2020. (Xinhua/Peng Yuan)

Fire fighters take part in an emergency drill against winter chemical hazards and accidents in Wuhai, north China's Inner Mongolia Autonomous Region, Nov. 25, 2020. (Xinhua/Peng Yuan)