BEIJING, March 28 (Xinhua) -- The quality of surface water near a site of a deadly blast has reached safe standards, the Ministry of Ecology and Environment spokesperson Liu Youbin said Thursday.

The ministry has sent 49 experts in environmental monitoring and treatment of water, solid waste and soil to help solve the pollution caused by an explosion at an industrial park in east China's Jiangsu Province on March 21, Liu said at a press conference.

All three waterways linking a local river to the industrial park have been dammed up to prevent polluted water from entering the river. The quality of surface water at all monitoring points meets the standard, he said.

Air pollutant concentration levels were within safe range at 2 km and 3.5 km downwind on Wednesday.

The deadly explosion happened at about 2:48 p.m. last Thursday, following a fire that broke out in a plant owned by Jiangsu Tianjiayi Chemical Co. in a chemical park in Xiangshui County, in the city of Yancheng.

The explosion killed 78 people and wounded hundreds as of Monday afternoon.