ASTM F2100 (North America)
ASTM F2100 grades surgical masks into three levels (1, 2 and 3) based on bacterial filtration efficiency, particulate filtration, differential pressure (breathability) and fluid resistance. Level 3 offers the highest fluid resistance for high-risk procedures.
- Level 1: low fluid resistance, general use
- Level 2: moderate fluid resistance
- Level 3: highest fluid resistance for surgery

