XI'AN - Environmental and public security departments of Southwest China's Shaanxi province on Monday proved that the water in Hanjiang River is clean after a tanker overturned and leaked its potentially polluting contents into the waterway.

After emergency measures conducted by various departments, the leakage of styrene - used to make polystyrene - has not polluted the water or had an impact on the lives of local residents, according to official tests.

The accident occurred at 2:40 am on Sunday on a highway in Ningqiang county, when a tanker overturned on the way from Hanzhong city, Shaanxi, to Sichuan. Two people in the vehicle were slightly injured in the overturn and about six tonnes of styrene passed into the nearby river.

The county's government set up three cofferdams to minimize pollution in the downstream of the Hanjiang River, and eight monitor stations in downstream areas to monitor water quality.

The area was evacuated of residents on Sunday, but they have now returned to their homes, according to the Environmental Protection Department of Shaanxi Province.