Blood donations are declining just as summer — typically a time of great demand for blood — begins. It's an annual problem, according to local blood banking operations.

But this year there's also speculation that rising gasoline prices will keep more potential blood donors away, as will the fact that more people than usual are selling their blood plasma to make money during trying economic times.

The blood experts say it's too soon to tell if such factors will have an impact on the blood supply.

"Summer's always tough, and we're noticing some decline — a little more than we would normally — but we don't know what to attribute it to," said Judy Christensen, spokeswoman for the local American Red Cross Blood Services. "Some people are making appointments they're not keeping, but why is not known. And the fact that they're making appointments at least means they're thinking of us, which is good."

She does believe that when money's tight and people are worried about putting food on the table, other things, like donating blood, may get lost. As for an impact from plasma sales, she notes that traditionally those who sell plasma and those who donate blood are not the same population.

Not having an adequate blood supply is never good news, regardless of why the decline in supply happens, especially when it coincides with an increased demand, said Karen Nielsen, vice president and group manager of ARUP Blood Services. But concern goes up in summer months, because that's when more people are out and about and "there are lots more ways for people to get into trauma."

The American Red Cross and ARUP supply most of the blood in Utah and to parts of neighboring states.

Where gasoline prices seem to be having an impact, Nielsen said, is in platelet donations, since those donors are asked to come in more often than whole blood donors. Platelets only last five days, and there's a constant need. Most whole blood — about 70 percent — is collected during mobile blood drives, while most platelet donors come to the centers. Add in (or rather subtract) the fact that there are fewer mobile drives in summer and you get a seasonal slump, she added.

American Red Cross Blood Services in Utah needs 450 blood donations every business day to keep adequate blood on hand to supply 40 Utah hospitals and facilities in parts of Wyoming and Nevada. Since blood is only good for a certain length of time, you can't sock extra away for tough times.

Only 2 percent of donated blood is not used, and that includes expired blood, that which didn't pass screening tests and the rare case when a bag breaks.

With luck, and barring catastrophe, ARUP expects to make it through June OK. July looks more problematic. ARUP supplies blood to University Hospital, Primary Children's Medical Center, Huntsman Cancer Hospital and Shriners Hospital for Children, as well as a hospital in Uintah.

To do that, they need at least 800 units of blood on the shelf, Nielsen said. ARUP blood has a shorter shelf life than the American Red Cross' because it is not collected in an additive solution, so it lasts 35 days instead of the usual 42. ARUP doesn't use the additive because many of the patients the blood goes to are children. "It's hard enough to manage one inventory" without having some blood for kids and others for adults, with different expiration dates. The children are given blood that came in within the past five days. Any that's not used in that time is rotated away from the children's hospitals to be used for adults, who are less sensitive.

An individual who sells plasma may still be able to donate blood, depending on a blood bank's policies. For instance, ARUP will defer a donor for eight weeks if there's a question as to how often that individual has sold plasma, Nielsen said. "We are very conservative."

Information on donating blood through ARUP is online at www.utahblood.org. The American Red Cross site is lewisandclark.redcross.org