Epidemic prevention remains a major challenge in areas downstream of the Tangjiashan quake lake, as water from it overflows, a public health expert said on Friday.

Although the water itself is relatively clean, it is bound to go through such places as hospitals, toilets and even chemical plants, and possibly mix with hazardous substances, professor Zhang Chaowu said.

"Precautionary measures have been taken to prevent outbreaks of disease after the draining of the lake," Zhang, an advisor to the Sichuan provincial public health department, said.

Experts have assessed the health risks in some key areas, where public health workers have been disinfecting for a couple of days, he said.

People evacuated to higher ground will be able to return home a few days after the draining has been completed, he said.

"But as long as people maintain good personal hygiene and keep the environment around their shelters clean, the flooding shouldn't have much of an impact on health," he said.

(China Daily June 7, 2008)