Full face masks / headaches

[BenQ]

I am an instructor for a 28 member Public Safety Dive Team. We dive primarily in cold water and use full-face masks and dry suits. We have both EXO 26 masks and AGAs.
Over the past two months several (9) of my divers have complained of severe headaches post dive. None of these dives exceeded no-deco limits and there were no rapid ascents or other mishaps. Also, all symptons resolved with no further problems. (The incidents all occured after deeper dives - 60+')
I am concerned about what seems to be becoming a fairly recent trend. After a little research I suspect Co2 build-up??? But, why now and not before.
Any other posibilities???

I have been researching US standards for "Class E" air and am finding conflicting numbers for Co2. Some sources say 500 ppm others say 1000 ppm. Anyone know??
(Canadian standards say 500)

The last test of our fill station showed 565 ppm Co2. This is an increase from the previous test which was 310ppm. Could this be part of the problem?

Any help appreciated...
Thank you
am

 

[BigJetDriver]

The last test of our fill station showed 565 ppm Co2. This is an increase from the previous test which was 310ppm. Could this be part of the problem?

Any help appreciated...
Thank you
am

You may have answered your question. You say that this is a recent phenomena. The increase in CO2 output by your compressor station may have been enough to push divers in high-workload situations over the CO2 edge, so to speak, especially if they are CO2 retainers.

 

[Bob3]

I'm guessing but I'd lean towards the CO2 culprit as well, if all other things were the same. Heavier workload & cold water might come into play as well.
Still doesn't sound scosh though.

 

[rmediver2002]

I would agree with you it sounds like CO2.

Do the headaches occur using both masks?

Are the oral nasal valves in good condition and properly installed?

Have you noticed any of the divers skip breathing / slow breathing / conserving air rates during training?

Your compressor is running well within range, CGA / OSHA / Navy standards allow for 1000 ppm Co2 (this is for both grade D or grade E breathing air)

Watch those air tests though, keeping a record of results can help you maintain your compressor...

 

[BenQ]

Headaches have occured in both masks.
All masks just went through annual maintenance in September.
Each diver is issued his/her own mask.
I did not notice anyone skip breathing. They know not to.....
Possibly; because we were training deeper than usual and much emphasis was put on keeping track of air in the classroom prior to the dive, folks may have been unconsciously trying to conserve air and breathing shallow.?
I will bring it up and have people double check their masks.
Thanks for the input.
am

 

[rmediver2002]

Hey Ben, double check your one way valves as well, they should be facing (folding) inward towards the inside of the oral nasal.

They should not allow any amount of air to escape from the oral nasal into the mask portion of the mask.

I have seen them installed incorrectly in the past...

On the EXO it is a good idea to update the oral nasal with the zip tie (locks it onto the regulator) the thin oral nasal can come off the regulator attachment point without and cause a buildup of CO2 inside the mask.

Also check that your mic is not touching the one way valve effecting function.

You may be right whether intended or not it is possible they were to some extent because of the training focus prior to the dive...