the rarest human blood type is called 'rh null'. although it can be used as a universal transfusion for all other blood types, the folks who have it cannot use any other blood. there are less than 100 known rh null folks in the world.

75% of the plastic pollution on earth (including the ocean) is dust from car and truck tires wearing down. the particles are so small that they pass directly from any animals gills/lungs into its blood, and from there to the brain. (that includes us.)

donated blood spoils in 42 days. because of this, much of the blood that is donated following a major disaster is sold or discarded, simply because the supply is too much to deal with in that small amount of time. it is better to regularly give blood than to give only when there is a disaster.