Dangerous chemical contamination remains in 19 warning zones around the site of the deadly explosion in northern China of Tianjin, according to the latest press conference held by Tianjin government officials on Aug 20.

Toxic chemicals including sodium cyanide, hydrogen sulfide, and hydrogen cyanide, ammonia, ethylene oxide, benzene, and toluene have been found in the blast zones. Some of these chemicals were exceeded limit prior to August 16, said Tian Weiyon, Ministry of Environmental Protection official.

However, the monitoring results after August 16 have so far been showing that benzene and the organic compound indicators are within the standard range at all zones, Tian said.

He said that the next cleanup step is to quickly clear up the toxic water now blocked inside the gutters and downspouts. The wastewater in there, if not cleared away, could later cause pollution once it rains.

Meanwhile, the air quality is normal, according to the observation of the chemical emergency rescue team.