Called "panda blood" because it's so rare, rhesus (Rh) negative is found in just three out of every 1,000 Han Chinese.

The supply of Rh negative blood is stable and adequate, says Wang Minghui, director of the rare blood group Home of Love at Beijing Red Cross Blood Center.

Established in December 2001, the organization has 1,142 members. Most are migrant workers and college students. It has collected almost 3 million cubic centimeters of blood in the past decade.

"When a rare blood donor gives 1,000 milliliters of blood, they are entitled to a lifetime of free blood," Wang says.

Niu Lianzhong has given more blood than this and also organizes Rh negative donations through the QQ forum.

Even so, the Rh negative teacher who lives in the suburbs of Shandong province's capital Jinan, says he has been falsely criticized for making money from his donations.

"We haven't been given any money at all," says Niu, who lives in a shabby house with his wife, where the sole appliance is an outdated TV set.

Niu says two-thirds of blood donors are aged 20-35. "But each person can only give 400 cc per year," he says.

The panda blood volunteers pay their own traveling expenses but do get leave from their jobs to donate.

"One solution is to connect more people with panda blood in different cities," Niu says.

"Blood source support can be mapped quickly. This will reduce costs and save lots of time."