The pressure inside the facemask is approximately in what range above atmospheric pressure?

The pressure inside the facemask is approximately in what range above atmospheric pressure?

• A. 0.02 to 0.04 psi
• B. 0.03 to 0.04 psi
• C. 0.036 to 0.054 psi
• D. 0.5 to 0.6 psi

Answer: (C)

Positive pressure inside the facemask is kept just above the surrounding air to prevent contaminants from leaking in through any small gaps in the seal. This tiny overpressure pushes air outward a little, so breathing air can’t be drawn in from the outside if there’s a slight leak. The typical facepiece differential is about 0.036 to 0.054 psi, which is roughly 1 to 1.5 inches of water. That small range provides reliable protection while remaining comfortable and not adding excessive breathing resistance. Values well below this may not fully prevent inward leakage, while much higher pressures would be unnecessarily uncomfortable and could impede breathing.

Positive pressure inside the facemask is kept just above the surrounding air to prevent contaminants from leaking in through any small gaps in the seal. This tiny overpressure pushes air outward a little, so breathing air can’t be drawn in from the outside if there’s a slight leak. The typical facepiece differential is about 0.036 to 0.054 psi, which is roughly 1 to 1.5 inches of water. That small range provides reliable protection while remaining comfortable and not adding excessive breathing resistance. Values well below this may not fully prevent inward leakage, while much higher pressures would be unnecessarily uncomfortable and could impede breathing.