He worked as a nurse in Michigan before coming to China to become a teacher.

Comfortably fluent in Chinese, he has no barriers in daily communication. He teaches at Shangqiu Normal University, based in Henan province, and often takes the train to visit his students in Qingdao during the vacation, donating blood at the same time. Often, he also takes students to donate.

Ruhstorfer earns about 7,000 yuan ($1,035) every month, not enough to cover the school fees for his children. "I decide to sponsor their tuition or room and board according to the income of their families," Ruhstorfer said.

"Ruhstorfer often takes his children to our service station so he can buy them gifts after donations," said Jiao Haiyan, a staff member at the Pingdu station.

He lives frugally.

"I don't smoke or drink, or eat at expensive restaurants. I take the slow train because the tickets are cheaper. And this shirt I have worn for years and I will be wearing it as long as possible."

He received Golden Awards for blood donation in 2014 and 2015.

"As a foreigner who can insist on donating blood without payment, Ruhstorfer fully reflects a love without borders and is really admirable," Dong Yongguang said.