If the protection factor of a full-face respirator is 50 and the breathing-zone fiber concentration is 300 f/cc, what is the estimated concentration inside the respirator?

If the protection factor of a full-face respirator is 50 and the breathing-zone fiber concentration is 300 f/cc, what is the estimated concentration inside the respirator?

• A. 3 f/cc
• B. 6 f/cc
• C. 60 f/cc
• D. 150 f/cc

Answer: (B)

The protection factor tells us how much the respirator reduces exposure: Inside concentration = Outside concentration ÷ Protection factor. Here, outside is 300 f/cc and the respirator PF is 50, so inside = 300 ÷ 50 = 6 f/cc. Therefore, the estimated concentration inside is 6 f/cc. The other values would require different PFs (for example, 3 f/cc would need a PF of 100), which doesn’t align with the given protection factor.

The protection factor tells us how much the respirator reduces exposure: Inside concentration = Outside concentration ÷ Protection factor. Here, outside is 300 f/cc and the respirator PF is 50, so inside = 300 ÷ 50 = 6 f/cc. Therefore, the estimated concentration inside is 6 f/cc. The other values would require different PFs (for example, 3 f/cc would need a PF of 100), which doesn’t align with the given protection factor.