Plasma is the liquid portion of your blood, making up more than half of your blood volume. Your kidneys adjust the composition of plasma to keep your body’s function in balance.

About 55% of your blood is composed of plasma. The remaining 45% consists of platelets and red and white blood cells, according to the Cleveland Clinic. Plasma plays many roles in the human body.

In an exclusive story, our team followed a donation of platelets, from the donor's arm to its grateful recipient, learning everything that happens in between.

The use of blood and plasma donations with higher levels of PFAS is a “big controversy,” according to study co-author Dr. Bruce Lanphear. The Red Cross, however, did not express much concern.