The woes for residents in China's Tianjin port city are far from over following the deadly explosion last week as the exposed sodium cyanide has the potential to release the lethal hydrogen cyanide if it rains in the region. 

Sodium cyanide, which is in a solid state in a powder form, releases the deadly hydrogen cyanide when it comes in contact with water, and environmental experts have raised an alarm of this happening as storms approaching the region could bring rains to Tianjin, NBC news reported. 

Hydrogen Cyanide is a lethal gas that can interfere with the body's ability to use oxygen, leading to death. 

"If there is rain, it will produce hydrogen cyanide, so we are monitoring it closely," Bao Jingling, chief engineer for the Tianjin Environmental Protection Bureau, told the news channel.

Hundreds of tonnes of sodium cyanide were found in the blast zone, forcing authorities to evacuate residents in a 3 km radius.

The scare comes just days after it was reported that the Tianjin blast had led sodium cyanide to leak into underground sewage drains, though it has not been detected in drinking water in the area, Chinese media reported. 

The death toll from last Wednesday's explosions rose to 114, and is likely to increase further as 70 people still remain unaccounted for.