Blood donations to the American Red Cross this summer are the lowest that the organization has seen in more than a decade.

The Red Cross announced a nationwide critical blood shortage Monday, and the Northern New England Region Red Cross issued an appeal for blood donors of all types.

“We want to make sure we have blood on the shelf for everyone in New England, in Maine, and across the states,” said Ellen Russell, the organization’s director of Maine relations.

The Red Cross Northern New England Blood Services Region provides blood to more than 80 hospitals.

More than 500 people must give blood and platelets each weekday to meet hospital demand.

This May and June, blood donations were 6 percent lower than what the Red Cross typically sees during those months. Russell said there are many contributing factors to the typical summer shortages: schools being out of session, heat that deters people from donating, people taking vacations.

“We encourage people to make this a part of what they do and who they are, to do it several times a year,” Russell said.

“We try to make donating blood very easy to do. It takes less than ten minutes to take the opportunity to really make a difference, to save someone’s life.”

Sharon Staples, a student at the University of New England, rolled up her sleeves and gave blood Tuesday in Portland.

“I’ve seen first-hand how quickly people lose blood in emergency situations and how important it is to have blood nearby and accessible at all times,” she said.

All blood types are needed, according to the Red Cross, but especially O negative, the universal type that can be used to treat any patient.

American Red Cross donation centers in Maine are in Portland, Lewiston and Bangor.

Individuals who are 17 years of age (16 with parental permission in some states), meet weight and height requirements (110 pounds or more, depending on their height) and are in generally good health may be eligible to give blood.

For more information, call 800-733-2767 or visit www.redcrossblood.org to find a blood drive and make an appointment.