What is the protection factor for a full-face respirator?

• A. 10
• B. 100
• C. 50
• D. 200

Answer: (C)

Protection factor is the amount by which a respirator lowers your exposure to contaminants, defined as outside concentration divided by the concentration inside the facepiece. For a full-face respirator, that value is 50, meaning the air you breathe inside is about 50 times cleaner than the air outside, assuming a proper fit and functioning filters.

For example, if the air outside has 100 units of a contaminant, the air inside would be about 2 units (100 divided by 50). Real protection relies on a good seal, correct donning, and well-maintained filters; a poor fit or leaks can reduce protection significantly. This APF is higher than what a half-face respirator provides but lower than powered systems with hoods, which offer much higher protection.