London Olympics 2012: Blood donor appeal ahead of Games
The health service is appealing for extra blood donations before the Olympics start in July.
NHS Blood and Transplant (NHSBT) says stocks need to be 30% higher than normal by the start of the Games.
The extra supplies are part of the contingency plans to cope with the extra visitors coming to the UK.
There are also concerns that donations may drop off during large national celebrations like the Diamond Jubilee and other major sporting events.
The situation has been described as a potential "perfect storm" of increased demand at the same time as falling supplies.
The Olympics and Paralympics are expected to bring an extra 1.2m visitors to the UK. That will include 15,000 athletes from every part of the world.
During major sporting events or national holidays, blood stocks sometimes dip as regular donors forget to make appointments.
Jon Latham, from NHSBT, told the BBC: "Every unit of blood saves or improves the life of three people. We obviously want to make sure everyone enjoys the Games, and want to make sure that if there are any accidents we have the blood supplies to help them recover quickly."
This summer presents a particular challenge for the blood service because of the unusual combination of events. There is an additional bank holiday for the Diamond Jubilee, as well as Wimbledon and football's European Championships.
During big sporting events, the number of donations drops as people miss sessions to watch their favourite sports. That is why NHSBT is hoping to increase the supply of blood just before the Olympics.
By starting with a high level of stock, they can allow it to taper back to normal reserves during the summer.
Each year 230,000 new donors are needed, so the appeal is partly aimed at getting people to think about signing up now rather than later in the year.
A lifesaving donation
Relatively little donated blood is used for treating people injured in accidents on the road or at work.
Blood is needed for a wide range of medical situations, from women giving birth who lose blood to helping those undergoing surgery.
Lucia Sarsby, who is 11 years old, is a patient at Bristol Royal Infirmary, where she has received regular transfusions of red blood cells since she was a toddler.
Lucia has a condition called beta thalassemia major, and is matter of fact about its consequences: "I can't make red blood and without it I would die."
Maintaining supplies to regular patients and also having enough reserves to cope with any contingency will present the blood service with a challenge.