Medical masks are also known as Procedural masks. They are classified by ASTM F2100 into levels 1, 2, and 3. Level 3 has the highest protection against bodily fluids spray (160 mmHg of pressure - think of a surgeon hitting an artery). Level 3 also has the highest bacteria and particulate filtration levels (>98%) through the mask media. However, medical/procedural masks aren't designed for a tight fit and there's often plenty of leakage around the edges. So the practical filtration can be considerably lower than with a KN95/N95 respirator. For this reason, respirators are recommended over medical masks for any airborne particulate or pathogens.