Haitian people should be aware of the dangers posed by unsafe buildings left by the devastating earthquake on Jan. 12, an official of the UN Environment Program (UNEP) said Friday.

It is necessary to ask the Haitian people to keep away from weakened buildings because they might collapse in aftershocks, Andrew Morton, program director of the UNEP, told Xinhua.

"We could use a system of red, yellow and green cards" to categorize the "unusable under any circumstances," the ones possible for "restricted use," and the "safe," Morton said.

He said conditions of many residential buildings need to be assessed by experts to "reduce the population's vulnerability," but "unfortunately people continue to use buildings that are extremely unsafe."

Morton said the UNEP is working with the Haitian Mining and Energy Bureau and the Communication Ministry to enhance Haitians' understanding of the risks.

The authorities issued a joint statement on Friday urging people to stay in temporary shelters.

"The second thing to do is to make sure the population take anti-quake measures," Morton said.

Haiti does not have anti-quake standards, and buildings were often built in the pattern of "concrete ceilings on weak walls," making them more likely to injure residents, he said.

(Xinhua News Agency February 6, 2010)