Human blood is needed — desperately — by the Red Cross.

Blood donations through the American Red Cross are at their lowest level in 15 years, a problem the agency proclaims in bright red letters with the words “Emergency need for blood” on its website.

“It’s unusual that we’d go on such an aggressive appeal to reach blood donors,” said American Red Cross Penn-Jersey Blood Services Region spokesman Anthony Tornetta. “We’re trying to talk to any organization that’s interested or has even considered thinking of hosting blood drives. ... Our team is on a daily basis making phone calls across the region, to schools, colleges, churches, whatever organization might be interested.”

A warm winter and spring may have led people to make plans that interfered with giving blood, Tornetta said. In addition, donations drop when high schools let out for summer, since 16-year-olds can donate with parental consent and 17-year-olds can do so if they meet height and weight guidelines.

Eligible blood donors are people ages 17 and older who weigh at least 110 pounds and are generally in good health.

“When they’re out on spring break or summer break, that’s units of blood that aren’t there,” Tornetta said. “It’s all culminated in a perfect storm.”

Across the country, Tornetta said, about 40,000 units of blood have gone “uncollected” in the past few months, meaning that the amounts estimated to be collected at each blood drive — taking into account metrics such as the size of the group and how much they’ve donated in the past — have fallen short by that amount.

Locally, Tornetta said, about 2,000 units of blood have gone uncollected.

“This year there has been more of a decline than in past years,” he said.

At the Pleasantville Donor Center, Volunteer Specialist Maureen Buehl said the Southern Shore Chapter holds 30 to 40 blood drives a month. Each pint given by a donor is usable for 21 days, but that person cannot donate again for 56 days.

“O-negative and O-positive (blood types) are the ones we need most,” Buehl said. “They can give to anyone. But right now, we need them all.”

All a group or business has to do to start up a blood drive is contact the Red Cross, she said, and they take care of everything.

“We set a date, provide all the marketing materials, and on the day of, we come out with everything we need,” Buehl said. “It’s that simple.”

According to the American Red Cross, once the donation is complete, the blood is scanned into a computer database, and most blood is spun in centrifuges becoming three distinct components: red cells, platelets and plasma.

The blood is stored in test tubes, which are tested in one of five Red Cross National Testing Laboratories to establish the blood type and to test for infectious diseases. Blood units found suitable for transfusion are then labeled and stored.

The Red Cross says red cells are stored in refrigerators at 43 degrees Fahrenheit (6 degrees Celsius) for as long as 42 days; platelets are stored at room temperature in agitators for as long as five days; and plasma is frozen and stored in freezers for as long as one year.

Tornetta said that for this region, which includes New Jersey and southern Pennsylvania, blood collected at an Atlantic County blood drive, for instance, is tested at a laboratory in Philadelphia and then made available to the approximately 100 hospitals in the region.

“We need 1,200 units a day to maintain a stable blood supply,” he said, adding that to supplement what is collected locally the region imports blood from other states.

Blood collected at a donation drive Friday at VFW Post 3509 in Wildwood would have been among the blood sent to those regional hospitals.

But when the drive began at 2 p.m. at the post meeting hall, there was just one person in line.

“This is the first time I’ve gone (to a drive) and didn’t have people sitting and waiting,” said Donna Webb, of the Villas section of Lower Township. “I can’t believe it.”

Webb began giving blood regularly in 1982, when she went to nursing school, “and I just continued ever since.” She tries to donate every two months, the allotted limit.

“There have been a couple of times I missed,” she said. “But now it’s of the utmost importance. I didn’t realize it was actually as bad as this.”

As Webb lay on the table, a second donor arrived and had the row of seats to herself.

“I’m a nurse, and I know it’s a necessity,” said Tina Ratti, of North Wildwood. “I give whenever I’m eligible. I’ve just started this year, but this is my third time this year.”

There were about 50 people scheduled to donate during the five hours the blood drive took place, but it was unclear how many eventually showed up.

While the system is set up so that blood needed in one region will be transferred to another, keeping up a steady supply of localized blood is important, Tornetta said.

“By donating blood, you may not know who it’s going to help,” he said. “But it might help someone in your community.”

In the end, besides seasonal issues, there is an explanation as to why more people don’t give blood, Buehl said.

“The number one reason most people don’t donate,” she said, “is that they’ve never been asked.”

Contact Steven Lemongello:

609-272-7275

Follow @SteveLemongello on Twitter

Contact Trudi Gilfillian:

609-463-6716