Pure ones have no excuse now that we know the appalling risks of receiving Impure tainted muck.
Find a relation or close friend immediately who is also pure and is blood group compatible and make sure you have some sort of way of making your necessary demands heard and acted on -- without discussion or argument if you bump into any of the Stupids with their know-all nonsense .
The easiest solution is to go in ahead of your surgery and donate your own blood.