School is out for the summer, and many north country residents are happily making vacation plans. But these are not carefree times for the American Red Cross.

The next few months will be the most difficult time for the nonprofit agency to collect blood donations.

Each summer, the number of donations drops at least 10 percent to 15 percent, said Francine Patella-Ryan, a spokeswoman for the American Red Cross New York-Penn Region. That represents the percentage of blood donations that are typically made by high school and college students through drives held at schools.

Blood donations are also down during summer because many people are on vacation, Ms. Patella-Ryan said.

"Donating blood is just not on their radar screen," she said.

The New York-Penn region, which includes Jefferson, St. Lawrence and Lewis counties, experienced a critical blood shortage last summer as did much of the rest of the nation.

The American Red Cross is putting out a call for businesses and organizations to step forward and sponsor blood drives this summer to help make up for the drop in donations.

Those interested in hosting a blood drive can contact the American Red Cross by calling 1 (800) 448-3543 or visiting the agency's Web site, www.DonateBloodNow.org.

The agency is also sponsoring several promotions this summer to recruit donors, and keep its loyal ones, said Ms. Patella-Ryan. They include the opportunity to win merchandise, T-shirts and travel vouchers.

It's estimated that only 5 percent of the eligible population donates blood. People age 17 and older who weigh at least 110 pounds and are in general good health may be eligible to donate.

Here's a quick look at how one pint of donated blood can help save as many as three lives:

The blood can be separated into red cells, plasma and platelets.

Red cells have a shelf life of 42 days, and plasma can be frozen up to a year. Both products can be transfused in an emergency situation such as severe internal bleeding.

Platelets have a much shorter shelf life (one week) and are typically used for cancer patients undergoing chemotherapy and radiation treatments

How much blood is really needed by hospitals? According to the Red Cross, a heart transplant takes four to six units of red blood cells. The same amount is needed for a patient who suffers an abdominal aortic aneurysm.

An adult undergoing open-heart surgery typically needs two to six units of red blood cells, two to four units of plasma and one to 10 units of platelets.

For newborns undergoing open-heart surgery, one to four units of red blood cells, one to two units of plasma and one to four units of platelets are often required.

It can take just one serious car accident to nearly wipe out a hospital's blood supply within hours. Patients involved in serious automobile accidents may need between four and 40 units of red blood cells.

The easiest way to donate blood is to check out the agency's Web site, which is very user-friendly.

Click on "Donate Blood," and a map of New York will appear. Then click on your county of residence to view an updated list of local blood drives.

In the words of the American Red Cross campaign, "Give a Little of Yourself This Summer."