2 recent deaths where snorkelers happened to be using full face masks

[tridacna]

I am curious then with this feature "No air from your mouth or nose enters the face cavity" How does one equalize pressure in the face cavity? So the mask is exclusively designed for surface use only?

This is a snorkeling mask only. It is not intended for diving.

1. You cannot equalize the eye pocket.

2. Unless you can use your tongue to equalize your ears, that’s not happening either.

We demonstrate use of the mask in the pool and all students are given full instructions about how it works and what not to do. We also do not sell to anyone under the age of 14. (Our own arbitrary rules).

You can freedive to 6-8 ft with no problems.

 

[Russell Bowyer]

Interesting thoughts about these full face snorkel masks and I don't know what happens to snorkelers in Hawaii, as they seem to have a higher percentage of fatalities than other places in the world, not just with the full face masks either.

There is an argument with them about the build up of CO2 and a snorkeler shouldn't exert themselves too much.

 

[tridacna]

Interesting thoughts about these full face snorkel masks and I don't know what happens to snorkelers in Hawaii, as they seem to have a higher percentage of fatalities than other places in the world, not just with the full face masks either.

There is an argument with them about the build up of CO2 and a snorkeler shouldn't exert themselves too much.

IMO I suspect that they may be using the cheap knock off FFMs. Seavu/ Head are the legitimate ones. Walmart sell a cheap knock-off “Seaview”.

Caveat Emptor.

 

[John C. Ratliff]

We have a thread going on Facebook about this. There was some testing done by Head and published on this site:

HEAD/MARES Comment On Recent Snorkeling Deaths In Hawaii – DeeperBlue.com

Here's the response I made to that testing:

Well, I spent some time yesterday going over the calculations to try to better understand what they really mean. To do this, I wanted to change the measurements to a value I could use to compare it to established standards. I know that the EU250 standard was 10 and 20 millibars, but that doesn't tell me much as an retired industrial hygienist. I needed that translated into parts per million (ppm) if at all possible. Well, it was possible, but I needed to make a couple of assumptions.
One was that these measurements were made at standard temperature and pressure (STP). I am using the American Association of Physicists in Medicine definition of standard temperature of 22 degrees C (72 degrees F), and 101.325 kilo Pascals (which is 1013.25 millibars). Dividing the measured level of CO2 in millibars by the atmospheric pressure in millibars of 1013.25 millibars will give us a percentage in the air, and then making the calculation will give us a reading in parts per million (ppm).

ppm = percentage in air x 1,000,000 / 100

Now, we in the industrial hygiene field use the American Conference of Governmental Industrial Hygienists' Time Weighted Average (TWA) for an allowed 8-hour concentration of chemicals. For carbon dioxide (CO2) in air for workers, this 8-hour TWA is 5000 ppm, with a Short-Term Exposure Limit (STEL) of 30,000 ppm. The highest reading that Mares measured in any of these masks was 2360 ppm using these assumptions.

Now, for my reservations; I am assuming that these measurements were made inside the nasal mask inside the Full Face Mask, which is what the person would have been breathing. I am also assuming the STP of sea level.
One other reservation I have is the assumption of a breath being about 4 liters, at the higher rate of 62.5 liters per minute (62.5 L/m). That gives about 16 breaths per minute. Looking at this, it indicates hard work, not a panicing swimmer. If we were to make other measurement of a breathing level of 1 liter per breath, and very rapid breathing, I think the results would be much higher levels of CO2 developing, as the snorkeler would be re-breathing most of his/her own breath and getting little outside air in some of these mask designs. There are a few masks which separate the inhalation and exhalation design within the snorkel, and it would be interesting to see what difference this makes is this scenario.

SeaRat
John C. Ratliff, CSP(Retired), CIH(2006-2017), MSPH

PS, here's the Facebook entry (I think):
Scuba Accidents and Risk Management Techniques for Divers

 

[A_G_Owen]

Hi guys,

We just did a research regarding the full face mask issue and we found the problem is usually the wrong design and the incorrect usage.

There is no official information so far that these masks caused the latest tragedies. The reason that could lead to dangerous CO2 buildup is the wrong design and lack of testing. Big manufacturers like HEAD-MARES joined the investigation to figure out what could happen as John C. Ratliff already mentioned. The test results prove that masks with the right design provide correct air circulation so CO2 cannot build up. The problem is with cheap copycat masks that are not tested out. From the other side, it seems people still dive with full face masks which is absolutely a BIG NO because they are designed for easy surface snorkeling only.

If you intend to buy a full face mask, don't buy noname models!

 

[GreggS]

I had the opportunity to try one of the full-face snorkeling masks a couple of years ago. I have never dove with a FFM so it took a couple of seconds to get acclimated to breathing thru my nose with my face in the water but once I got past that it was quite enjoyable. And while I only used it for a few minutes, I didn't get any feeling of breathing difficulty nor did the vision lens area fog at all.

The owner of one the the LDS's I frequent says he has sold several of these masks. Of course he only sells the upper end ones so there have not been (so far) any issues with the ones he has sold.

 

[Russell Bowyer]

It surprises me that people even consider diving with a FFM - it would be near impossible to equalise with a full face mask! And I'm not taking about the ones designed specifically for scuba diving when I say that

 

[tridacna]

It surprises me that people even consider diving with a FFM - it would be near impossible to equalise with a full face mask! And I'm not taking about the ones designed specifically for scuba diving when I say that

It is impossible not “nearly” impossible to equalize with a snorkel FFM.

 

[woodcarver]

I looked at some of these and tried one on thinking it would be pretty cool in the water. The field of view is really good. And it was very comfortable and sealed well. But I hung up on the price, $99, and passed.
Found a couple YouTube reviews that were pretty good. Main problem is inability to equalize the way most do if you want to dive down to look at something. I don't think that would be a problem for me as I normally just swallow, don't need to pinch the nose. But the Aussie doing the review specifically talked about not swimming hard as it made it more difficult to pull enough air. I wonder if the snorkel tube is simply too small a diameter? It's not very long. The one I tried on had exhaust valves in the mouth/nose portion.
It will be interesting to see if they determine these masks played a part in any of the deaths. The guy at the shop said they sell quite a few of them, despite the price tag. Wouldn't surprise me if a suit gets filed simply because the question of CO2 buildup has been mentioned in a number of these unfortunate deaths.

 

[tridacna]

You can’t equalise the eye cavity no matter how hard you swallow or chew. I’m sure you know that you can exhale through your nose to equalise that space in your regular mask - you just can’t do it in a FF snorkel mask. Might have an interesting effect on your eyeballs at 30 feet. I wouldn’t try.