It's just past noon and 40-year-old Zhao Hongwei is getting ready to climb a 40-meter power tower to carry out routine maintenance work, shortly after finishing a seven-kilometer patrol on foot 2,600 meters above sea level.

Spring in Southwest China's Yunnan province can be hot and the temperature has already climbed to 32 C.

Even for someone who is fit, the plateau's weather can be unbearable, resulting in dizziness, nausea and difficulty breathing.

But for Zhao, it's just another normal workday. "In summer the temperature can hit 40 C. That will be unbearable. It's also the time when leeches and snakes come out," Zhao said.

Zhao works at Yunnan Power Transmission and Transformation Engineering Co Ltd, a subsidiary of China Southern Power Grid, the country's power major covering the Guangxi Zhuang autonomous region and Guizhou, Guangdong, Hainan and Yunnan provinces.

The company is known for its West-to-East Electricity Transmission Project. The project transmits clean power from Southwest China to the Guangdong-Hong Kong-Macao Greater Bay Area, and Hainan province.

While many people applaud the grand project, few know anything about the 300,000 workers that make the project possible.

Among them, there are many power line technicians like Zhao, who work 25 days a month and walk 20 km per day on average just to make sure that nothing is wrong with the power lines.

"I'm proud of what I do, and so is my son. He always tells his classmates that his dad is a 'flying man'," Zhao said.