Contrary to popular belief, offering a reward for blood donations isn’t such a bad idea.

When a natural disaster strikes, whether it’s a historically tragic tornado, a super storm, or a rash of exceptionally bad wild fires, there is plenty and more the unaffected can do to help the victims. One thing most able-bodied adults can do to help is donate blood. But while blood donation seems simple, there often isn’t enough donated blood to go around during a crisis.

Three economists are now suggesting a fix for blood banks left high and dry—offer incentives for donation. While giving a reward for a blood donation seems obvious, it hasn’t been common practice during the past 40 years.

The thinking goes that blood donations will be of the highest quality if they come from volunteers, not if the donations have been incentivized. But that’s not the case, say the economists in a recently published policy article in Science.

“Blood supply shortages are a major health problem in developed countries and even more severe in lower-income regions,” said study author Nicola Lacetera, Ph.D., of the University of Toronto, in an interview with Healthline. Because donations have long been simply that, donations, Lacetera wondered what might kick-start the flow of blood to areas that need it most.

“[There are] several contexts where individuals might respond to multiple motivations, intrinsic and extrinsic, and in investigating how these different motivations interplay. The case of blood donations is a relevant one,” Lacetera said.

Agencies like the American Red Cross and the World Health Organization dictate safe practices for blood donations, but it’s possible they’ve been approaching the process in a less-than-ideal way.

“There is a broad view that offering material incentives for activities that are done for altruistic reasons or ‘intrinsic motives’ might backfire,” Lacetera said.

However, after examining studies of different blood donation practices, including recent field studies of large, representative populations, it appears that incentives like gift cards and free medical tests have no negative impact on the quality of blood donors.

This means that in instances where more blood is needed quickly, offering a reward could be quite useful. And the type of reward matters.

“Positive response to incentives in the field studies is greater for non-cash incentives of higher economic value, at least within the rage of values, between $5 and $20, analyzed in the existing studies,” Lacetera said.

It’s important to note that the incentives were given just for showing up at the blood donation site. “Because the reward was not dependent on donating blood, the risk of misrepresentation of health or other information by an ineligible donor who wishes to receive the reward is reduced,” said Lacetera.

Following a disaster like the Oklahoma super-tornado or the recent Boston Marathon bombing, when the need is highest, donations appear to follow suit. However, incentives could still be used to increase the pool of available donors, especially under normal circumstances.

“In such tragic circumstances, people do respond to a number of motivations. We saw it after September 11th…and in addition to the Oklahoma tornado, following the Boston Marathon bombing, with runners lining up to donate blood,” Lacetera said.

But constantly maintaining and replenishing blood bank supplies will help assure there are plenty of resources to go around in times of need.

“Emergencies and appeals in certain circumstances are very powerful, and this is reassuring to see,” Lacetera said. ” However, the shortage of blood is constant, and in ‘normal’ times, small material gifts like those analyzed in the studies we reviewed seem to work well.”