Staff members of Fire and Rescue Headquarters command rescue work near the explosion site in Binhai New Area of Tianjin, north China, August 13, 2015. The death toll has climbed to 44 from two massive blasts that ripped through a warehouse in north China's port city of Tianjin as of Thursday noon, according to rescue headquarters. Twelve firefighters were among the dead. Photo: Xinhua

Staff members of Tianjin Environment Monitoring Center monitors air quality near the explosion site in Binhai New Area of Tianjin, north China, Aug. 13, 2015. The death toll has climbed to 44 from two massive blasts that ripped through a warehouse in north China's port city of Tianjin as of Thursday noon, according to rescue headquarters. Twelve firefighters were among the dead. Photo: Xinhua

Staff members of Tianjin Environment Monitoring Center monitors air quality near the explosion site in Binhai New Area of Tianjin, north China, Aug. 13, 2015. The death toll has climbed to 44 from two massive blasts that ripped through a warehouse in north China's port city of Tianjin as of Thursday noon, according to rescue headquarters. Twelve firefighters were among the dead. Photo: Xinhua