The air and water quality in the blasts area in north China's Tianjin is being closely monitored, as on-site conditions are still unclear.

"So far, the air quality near the blasts site has indicated normal, and might not cause harmful results to residents," Feng Yinchang, an environmental expert told a press conference Friday morning.

Some monitoring stations detected toluene, chloroform, methylbenzene and volatile organic compounds, all hazardous pollutants, from Wednesday night to Thursday noon, but the densities decreased because of winds blowing, Feng said.

As of Thursday noon, all toxic gas indicators were within normal range. The quality of air and water will continue to be closely monitored, Feng said.