Blood banks on the east coast launched a public appeal last Monday announcing they had one day's supply of O-negative blood, the lowest in more than five years.

The shortage was a direct result of a record flu season causing roughly 3000 donors across the country to cancel their appointments because they were sick with a cold or the flu.

Canberra's Red Cross Blood Service experienced a 14 per cent cancellation rate, equating to 90 fewer donor appointments in the past week alone.

To claw back supply it has launched an open door policy waiving the need for anyone with the O-negative blood type to make an appointment to donate.

At least 78 new ACT blood donors have been recruited since the national public appeal kicked off on Monday in the ACT.

So far 90 O-negative blood donations have been made, eight of which were from new donors.

Eddie Wheeler, 74, had not donated for two years before he stepped up on Wednesday to give O-negative blood after hearing the "call to arms."

"It reminded me of the need to do be doing it again," he said. "It's a feel-good process; a painless exercise and an uplifting experience because you know you are doing good for the community."

In an emergency, type O-negative red blood cells may be given to anyone, which is vital especially if the situation is life-threatening and there is no time for questions or the matching blood type is in short supply.

About 8 or 9 per cent of the population had O Negative blood.

However, the indispensable blood product used by hospitals and emergency services is always in high demand and constitutes close to 15 per cent of all blood products distributed by the Australian Red Cross.

The predicament for blood banks is that more than 50 per cent of Australians don't know what blood type they are.

Red Cross has urged Australians to donate and find out.

"We'd encourage people who don't know their blood type to make an appointment to donate and find out," Red Cross blood service spokesman Jemma Falkenmire said.

"It's also helpful to know you blood type in case of emergencies, but also to know when your blood is needed."

People can donate blood at the Canberra Donor Centre in Garran or at various mobile donor centres around the city.