(CNN/Gray News) – When you think about donating blood, it's probably a reaction to something.
The Red Cross says only 3 percent of people in this country who can give blood do so, and tens of thousands of donors are needed every day.
Maybe someone in your life has been in an accident or there's been a natural disaster or a mass shooting.
"The irony is the patients who suffer from those tragedies, actually they're alive because people days before had given blood to make sure that it's readily available," according to Cliff Numark with the American Red Cross.
There's extraordinary demand for blood in the United States. Every two seconds in the U.S., a patient needs it.
But there's a problem.
The Red Cross says only 3 percent of people in this country who can give blood do so and tens of thousands of donors are needed every day.
That's where Facebook thinks it can help.
"We're going to put a notice right at the top of news feed asking people to register if they want to," Facebook Chief Operating Officer Sheryl Sandberg said.
"And if you register with our partners, like the American Red Cross, if there's a need for blood in your city, they're going to be able to notify you."
People also can sign up to be a blood donor on Facebook by going to "blood donations" in the About section of their profile.
It's something Facebook has already done in four other countries, signing up more than 35 million people as blood donors.
But of course, that's no guarantee people will actually donate.
Or that they'll trust Facebook to facilitate that happening.
"With blood donations we're not using or giving out any personal information. We show you a notice. You choose to go to a partner site like the American Red Cross and register," Sandberg said.
"They'll send you a notification and then you can choose to give them your information. We're not passing any individual information at all."
The Facebook push comes just ahead of World Blood Donor Day on Friday.
To find Red Cross blood drives near you, click here.
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