BEIJING - The capital is battling a 10 percent drop in the daily supply of blood from donors at a time when there is usually a rise in demand, according to Beijing Red Cross Blood Center.

Hao Xueyun, a native of Ulanqab, the Inner Mongolia autonomous region, donates blood in a donor bus at Jinyuan Times Shopping Center in Haidian district on July 14. Zhou Wenting / China Daily

The main donor groups, university students and migrant workers, dwindle during the summer because they return to their native provinces for holidays or summer harvests, Liu Changli from the center told China Daily.

As a result, the daily volume of collected blood has fallen below 1,800 units (a unit is 200 milliliters) since the start of July - 2, 000 units is the ideal volume to cope with clinical needs.

About 60 percent of donors are university students and migrant workers, according to figures from the Ministry of Health.

Apart from the reduced supply, a marked rise in demand is also expected because many people outside Beijing flock into the capital for surgery during the summer, Liu said.

"We prioritize blood needed for urgent surgery and have an understanding with hospitals that people should be advised to consider delaying non-urgent surgery until autumn when blood supplies from voluntary donations pick up again," he said.

To ensure a balanced supply of blood throughout the year, the Beijing Blood Center launched a campaign in June encouraging people to donate and stay on call for emergencies.

Some Beijing residents who signed up have already received messages from the blood center requesting them to make blood donations, Liu said.

Yin Zheng, 24, works at the Beijing Volunteer Federation and has been actively involved in the blood drive. He praised a recent initiative by the municipal authorities to invite donor representatives to group activities such as going to the cinema and landscape visits.

"Blood donors have the chance to get to know each other and form a close community that can inspire more people to join in the blood drive," Yin said.

Hao Xueyun boarded the donor bus in front of the Jinyuan Times Shopping Center in Beijing's Haidian district at 12:10 pm on Thursday.

"All of my colleagues, except a woman whose weight disqualified her, have come to donate blood. I am the last one," said the 20-year-old native of Ulanqab League, the Inner Mongolia autonomous region.

It was the first time Hao, a saleswoman in a cosmetic store in the mall, had donated blood.

The only blood donating building in the city is at Xidan, the city's central shopping area.

"We don't have many donors today, but maybe we will get more - there are usually 60 on the weekend," said the nurse, Jiang Lei.

Wang Shuang, a 19-year-old student from Jinzhou, Liaoning province, was one of six people resting on sofas after donating blood.

"My sister committed suicide six months ago, which was the first time I realized life can be so fragile. So I want to do more in my life for myself and for others," said Wang.