FAST FACTSWho can give: You must be 17 years old, or 16 with parental consent, weighing at least 110 pounds and in good health.What to expect: The process of donating usually takes 30 minutes and includes a complimentary snack and T-shirt.How to prepare: Drink plenty of fluids - avoid caffeine - and eat a meal rich in iron.Where to donate: Check out www.bloodassurance.org for donation times and locations.Source: Blood Assurance
Blood Assurance in Chattanooga says it has been short of O negative type blood all year, and now it is desperate for donations.
"It is hard because O negative donors are such a small percentage of our population," said Bonnie Phillips, media relations and development associate at Blood Assurance.
A little more than 6 percent of the population has this blood type - which is called the universal blood type because it is the only blood that can be given to anyone.
O negative blood is in the highest demand in hospitals since it can be given in an emergency when a patient's blood type is unknown, according to Phillips.
As of Friday afternoon, Blood Assurance had 22 units of O negative blood, a fraction of the 150 units it wants to have in stock, Phillips said. One donor provides three units of blood.
More than 400 blood donors are needed each day to adequately supply the 47 counties in Blood Assurance's region.
"If we have a slow day, like when it snows or people have the flu, we struggle to catch up for weeks," Phillips said.
Allison Callari, a junior at Clemson University who is from Chattanooga, said she found out that she has O negative blood this summer.
"Once I found out my blood type I realized that I had to keep giving," she said. "I plan to keep giving blood every time I come into town."