Residents were reminded again: Spitting must stop, starting now.

With the 2008 Beijing Olympics just 500 days away, officials said Wednesday they are prepared to take harsh measures against people who spit in public if appeals do not work.

"Very soon you will see action to stop spitting," Jin Dapeng, director general of Beijing's municipal health department, said. He refused to give specifics, but hinted that fines might be involved.

Residents say the habit is a reaction to Beijing's dirty, dry air.

Jin said the city has been successful in altering bad habits before, as during the SARS outbreak in 2003. "During the SARS period, people followed rules to wash their hands and they didn't spit," he said.

Bad manners have been a constant worry for Chinese officials and leaders who see the Olympics as a chance to impress the world and humanize China's remarkable re-emergence as a global power.

Delegates to meetings of China's legislature and a top government advisory body in Beijing this week have also voiced concerns about manners.

At a discussion panel Thursday, one adviser, Zi Huayun, listed four key bad habits of Chinese: spitting, not waiting in line, widespread smoking and swearing in the Beijing dialect.

Dirty toilets and rudeness were added to the list by He Huixian, vice president of the Chinese Olympic Committee.

"Acting civilized isn't something you do the day before the games," she said. "It's something that society has to absorb in its roots."

In another frank admission, Jin said the city had identified 45 possible health risks during the 2008 Olympics. Most centered on food and water safety, he said.

Jin said Olympic venues would be closely watched for flies and mosquitoes, common summertime pests in Beijing, and a food inspection monitoring system was in place for all the city's 35,000 eating places.

He said it was encouraging that no food poisoning cases were reported at street fairs held during the recent Chinese New Year holidays.