A respirator only protects if it seals
The filtration rating of a KN95 is measured on a sealed test rig, not on a real face. If the respirator does not seal against the wearer's face, unfiltered air leaks around the edges and bypasses the filter entirely. This is why fit is as important as the filter media β a high-efficiency respirator with a poor fit still lets contaminated air in. For healthcare and industrial use, a secure seal is the difference between protection and no protection.
- The rating is measured on a sealed test rig
- A poor fit lets unfiltered air leak around the edges
- Fit is as important as the filter media



