Canadian Blood Services is putting out the call to Canadians to encourage them to donate blood before taking summer vacation, so that supplies don’t run any lower.

The agency says it needs about 4,300 more people to roll up their sleeves and donate between July 16 and Aug. 6, in order to top up the current supply.

Canadian Blood Services' Senior Executive Director Mark Donnison says the agency is able to look ahead and anticipate shortages by looking at their donation appointment system.

“And we’re seeing a gap in appointments for blood donations across the country. So we have about 4,300 appointments that are left to be filled over the next three weeks,” Donnison told CTV’s Canada AM Tuesday from Ottawa.

“We’re reaching out to Canadians and asking them to fill those appointment slots to ensure that we have enough blood products across the country to meet demand.”

Donnison says blood reserves in several provinces are below their target levels; the problem is most noticeable in Canada’s larger cities, such as Vancouver and Toronto.

‘In general, we are seeing a softness across the country,” Donnison says.

Canadian Blood Services collects around 850,000 units of blood a year and the need for blood donors never wanes throughout the year. In fact, almost every minute of every day, someone in Canada needs blood. But Donnison notes that needs tend to increase during the summer.

“In addition to having to having to meet ongoing demand for blood products for such things as cancer treatments, we also see a spike in demand as result of car accidents over the summer,” he says.

South of the border, the American Red Cross has been experiencing one of its worst blood shortages in years. It issued a call at the end of June to say its blood supply has reached “emergency” levels, with 50,000 fewer donations than expected in June.

It said an unseasonably early start to summer weather might be a contributing factor to this year's shortage; many regular donors got an early start on summer activities and haven’t been taking time to donate.

Donnison says his agency is aware that many of those who have appointments booked won't make it; in fact,  only about 60 per cent actually show up for appointments. And he understands that people get busy during the summer.

“We do see in the summer months with people taking vacations, travelling, spending time with their families that blood donation doesn’t always make it to the top of the list of priorities for people,” he says.

But he adds that donating blood takes only about an hour of one’s time.

The donation process is fairly simple: After filling out registration forms, potential donors are screened through a couple of oral and written questionnaires. Then there’s the few minutes on the bed for the actual donation, followed by some time for refreshments and a quick checkup.

“So usually in 60 minutes, you’re in and out of the clinic. And it’s quite a neat experience overall,” he says.

To book an appointment to donate, visit blood.ca or call 1-888-2DONATE or 1-888-236-6283.