Under the burning sun in a temperature of 33 degrees Celsius, 48-year-old Dang Jianbin is sorting out dozens of packages outside an office building near Beijing's second ring road.

It’s almost lunch time, but he hasn’t had his breakfast yet. Dang’s only hope on such a hot day is to finish sending all the packages to their owners early and then rest in the shade.

"I have no better options than working in the heat,” said Dang, a delivery man for one of China’s top courier-service companies, which he said he could not reveal without permission. "I have to make a living by doing this to support my children and my parents.”