Khristenko said he also worried about the visitors. "What would happen to them when they wait for hours in the summer heat?"

A British father, who refused to be named, waited for some 15 minutes outside his country's pavilion and decided to give up. "My son is only about one year old. It'd be too much for him."

LABOR DAY

The Shanghai Expo opening day is the Labor Day in the real sense for thousands of cleaners, bus drivers, volunteers and salespeople who keep the Expo park running.

"We need to clean the bathroom once every 20 minutes," said Chen Huamei, who works in the media center. "It was really tough to start with."

Chen, a migrant worker from Anhui Province who eked out a living by offering domestic help to Shanghai families, actually takes pride in the new job. "My son says the Expo has been going on for more than 150 years but it's the first time for China to play host."

To work in a 5.28-sq-km area is by no means easy.

Xu Jie, a 20-something migrant from the northern Hebei Province, works to entertain visitors in a fluffy blue outfit to play Haibao, the Shanghai Expo mascot.

Xu and his colleagues stand at franchise stores to greet customers and pose for photos with them upon their request.

At 50, Aunt Xu, a native Shanghainese, took the toughest job in her life: cleaning streets and outdoor seats in the park. "I start working at 2:30 a.m. and clean up everything before the park opens."

Xu walks at least 5 km a day in an area near the UFO-shaped Cultural Center, where the dazzling Expo opening ceremony was held Friday. "When the Expo ends in six months, I'd qualify for a Marathon race."

Despite the tiring job, Xu said she enjoys telling her family about what happens at the Expo at the end of the day.