Head/Mares Discovers the Reason for Full Face Mask Deaths

The most successful full-face snorkeling masks evolved from those used successfully by Italian fire-fighters -- Ocean Reef. They proved popular with the public because they pitched it to people who didn't like getting their faces wet. Soon, lots of manufacturers elsewhere jumped on the full-face bandwagon.

Then people started dying while using them, which led to their getting banned in Hawaii. So, Head/Mares, a company that sells the Ocean Reef Aria full-face snorkeling mask under a different name (as do some other Italian scuba gear brands), decided to do some research.

Trapped carbon-dioxide, the gas we exhale as a side-product of metabolism, appears to be the culprit in snorkeling mask deaths, say Mares. It's the gas that gives us the incentive to exhale, and any more than a tiny percentage in the air we inhale can lead to breathlessness, distress, and finally, death.

So, what's going wrong? Head/Mares tested a range of these masks available worldwide, alongside its own product. What they discovered was alarming. Some of these masks provoked CO2 poisoning (hypercapnia) within minutes of use. It's because they don't sufficiently vent the exhaled air (loaded with CO2) from the air to be inhaled. This causes a build-up of poisonous CO2 within the mask.

Added to that, some users might not be physically fit and take shallow breaths, which encourages an internal build-up of CO2 within the user's own lungs. Together, the combination can be fatal.

If you want to use a full-face snorkeling mask, buy one with a well-fitting internal bib, and use it properly. You should always breathe deeply, being sure to empty your lungs as much as possible between breaths, and you should know how to rip the mask off easily should you encounter any discomfort or breathlessness. Tell your friends.

- John Bantin