Which prevention measure helps prevent facemask squeeze during ascent?

• A. Descend rapidly to release pressure
• B. Equalize pressure in facemask during ascent, no goggles
• C. Hold breath to counter pressure
• D. Increase buoyancy by rapid kicking

Answer: (B)

As you ascend, the pressure outside your face drops. If the air space behind your facemask isn’t equalized, a vacuum can form and the mask will squeeze against your face. The best way to prevent this is to equalize the pressure inside the mask during ascent. This is done by gently exhaling through your nose into the mask (keeping the mouth closed) to let air flow into the space behind the lens, so its pressure matches the surrounding water. Do this early and often as you rise.

Descending rapidly would not prevent mask squeeze during ascent and can introduce other problems. Holding your breath while ascending is dangerous because it can cause lung overexpansion injuries. Rapid kicking to boost buoyancy changes your ascent rate and pressure changes inappropriately rather than preventing squeeze.