Which statement about protection factors is true?

• A. Half-Face typically 50.
• B. Full-Face typically 100.
• C. PAPR full-face typically 50.
• D. Supplied Air typically 100.

Answer: (D)

Protection factors measure how much a respirator lowers your exposure to contaminants, defined as the concentration outside the respirator divided by the concentration inside it. Supplying clean air from an external source through a hose means you’re breathing air that hasn’t been contaminated by the workplace—your air supply isn’t filtered in the same way, so the protection level tends to be higher. In many training references this type of supplied-air system is described with a protection factor around 100 or more, making it the strongest general statement among the options.

The other statements clash with typical expectations: a half-face respirator relies on filters and a good seal, so its protection is generally lower; a full-face respirator with filters is better than a half-face but still usually not as high as supplied air; and a PAPR’s protection depends on whether it’s a loose-fitting or tight-fitting design, leading to a range of values rather than a single “typical” number. Because supplied air is not limited by filtration performance or seal leakage in the same way, its protection factor is consistently high, which is why this option is the best choice.