The number of visitors to the area rose from 13,374 in 2008 to 73,000 in 2012, according to figures provided by the Dingri county tourism bureau. In 2008, the zone received 2,698 foreign tourists, but by 2010 a record 18,700 foreigners visited the area, the highest number for five years.

More tourists, revenue

"We get more tourists and more revenue, but also more challenges and problems as well," said Xiong Jianbiao, director of the "110" help line at Dingri's public security bureau.

In the first 10 months of this year, the county's police station responded to 151 calls for help from tourists, 127 of them from tourists on Qomolangma.

In most cases, the tourists had experienced altitude sickness or become lost because of their unfamiliarity with the roads, according to Xiong.

"We have to respond, and the situation is just within our control. But it has grave implications because of the limited number of police officers available."

Tashi Dawa, head of the border police station at Qomolangma, said his officers receive four or five calls for assistance during the peak tourist seasons.

As an example, he spoke about a man from Shandong province who last year used the Internet to study the routes other trekkers had used. The knowledge he accrued allowed him to evade the police checkpoints as he attempted to ascend further up the mountain. A number of officers from Tashi Dawa's station had to be dispatched to search for the man when he lost his way.

Climbing to areas higher than 5,500 m is classed as mountaineering, not trekking, and those who wish to do so must submit an application to the local mountaineering association, which checks their eligibility. Climbers must also pay a hefty registration fee, which can be as much as 200,000 yuan ($33,000).

"Searching for missing people is not our main responsibility, but we have to do our best to save people's lives," said Tashi Dawa.

Galsang Drolma, an assistant researcher at the China Tibetology Research Center, said decision-makers in the autonomous region should consider the negative side effects and constraints when they formulate policies to develop the area into a world-tourism destination. She said the policies should examine the "ecological and infrastructure capacities and the adaptability of the locals to the development".

She also suggested establishing a system to monitor tourism projects, emphasizing that it should evaluate service standards and the real-time risks to provide tourists with a safe service and accurate information.

Dingri county is currently without electricity. The outage, which has been ongoing for two months, is the second to have happened this year as a result of insufficient capacity at the local hydroelectric station and poor performance during the "low-flow" period. The best hotels in town have restricted the use of generators to three hours a day, from 9 pm to 12 pm, while government officials only power up their generator when they want to send e-mails.

He Xianjiang, a local official, said he goes to bed at about 8 pm most evenings, once work is over for the day "because civil servants shouldn't go to teahouses too often, and it's too cold to leave your hands outside the quilt when you're reading."

Electricity is even more of a luxury in Zhaxizom village, about 40 km from Qomolangma. The residents are determined to develop the tourism industry, which has generated 5 million yuan so far and raised the annual per capita income of the 7,004 villagers to 40,000 yuan.

Many villagers earn a living by running guesthouses, working as yak porters and guides or as rubbish collectors at the camp.

"My younger brother is a tour guide. He is learning English in Lhasa," said guesthouse owner Galsang Tendron.