nitrox downsides

[bardass]

Overly active imagination, vulnerability and naivity possibly combined with a strong belief in conspiracy theories.

Another possibility is that this particular lady doesn't fully understand the complexities and proper usage of nitrox and experiences a moderate degree anxiety when she knows she'll be diving with it. To ease her anxiety prior to the dive she smokes a few cigarettes before splashing...

You're talking **** ...
You don't know this diver, yet you're imagining what she might be like, what she might believe...

I am a nitrox and trimix instructor in France, Oc and CCR.
My colleagues and I encourage all divers to use nitrox and trimix as much as possible.

We trained this lady in nitrox diving given her age and physical condition. She is enthusiastic and request about nitrox when the shops couldn't supply it.

Several months after her training, we noticed her hoarse cough when she came up from her dives.
She also told us about a burning sensation in her lungs and dry mucous membranes.
These are known effects of oxygen therapy.
But I had never encountered such cases with the use of nitrox in diving.
It is a fact that some divers are much more sensitive than others to oxygen inhalation.
Unfortunately, this diver now dives much less than before (she has gone from 30-40 dives to less than 15 dives per year) because she still wants to dive with nitrox and not use air.

Nitrox has enormous advantages in terms of decompression and safety.
Even if the reduction in fatigue is a placebo effect, it doesn't matter as long as the diver feels good.

But it also has disadvantages depending on the sensitivity of the divers.
There is no point in hiding this and mocking those who suffer the consequences.

 

[crofrog]

Several months after her training, we noticed her hoarse cough when she came up from her dives.
She also told us about a burning sensation in her lungs and dry mucous membranes.
These are known effects of oxygen therapy.

Is she a smoker?

 

[jborg]

It is a fact that some divers are much more sensitive than others to oxygen inhalation.

If this is indeed a fact, it must be rare enough that most divers will not have heard of it -- or have cause to hear about it...

 

[crofrog]

Ok, so lets assume all of that stuff and the references you posted are all valid and there is some slight advantage/safety margin to breathing trimix at depths greater than 100 up to the 130' limit (for recreational divers so certified).

It's not practical or economically feasible to pay for, nor for dive ops and shops to supply trimix (and the required equipment to produce it) to millions of recreational scuba divers.

It's like saying we should all carry a backpack with a parachute inside of it whenever we board a commercial airliner.

The analogy comparing trimix use in recreational diving to parachutes on airliners overlooks a critical distinction. Parachutes address extremely rare, high-consequence failures in the safest industry in existence, while gas density, narcosis, and CO₂ retention affect every diver on every deep dive.

In risk management, not all risks can be eliminated, but they must be visible and understood. Divers must assess their own risk tolerances, yet current recreational diving curricula across Open Water, Advanced Open Water, and Deep Diving certifications from major training agencies fail to address these physiological hazards. At depths between 100 and 130 feet, gas density and CO₂ retention are rarely discussed. As a result, divers are often unaware of the trade-offs they are making or the potential benefits of using helium-based mixes to improve safety.

Citing cost or economic feasibility as the primary reason to avoid trimix use in recreational depths is a flawed approach to safety. Cost is a factor, but it should not be the deciding factor. If cost were the main filter for risk management, we would not use redundant regulators, dive computers, or surface signaling equipment. Many accepted safety practices in diving carry additional costs, yet are widely adopted because they reduce the likelihood or severity of incidents. The value of a mitigation strategy should be based on its ability to reduce risk, not just its price tag.

 

[gamon]

Several months after her training, we noticed her hoarse cough when she came up from her dives.
She also told us about a burning sensation in her lungs and dry mucous membranes.
These are known effects of oxygen therapy.
But I had never encountered such cases with the use of nitrox in diving.
It is a fact that some divers are much more sensitive than others to oxygen inhalation.

Ok well that's rather odd and it's the first time I've ever heard about such a thing, however I'm willing to accept it may have some merit. It's certainly more believable than the debunked notion that nitrox makes divers feel better (possibly true only in cases where a diver on air is experiencing a very mild form of DCS).

this diver now dives much less than before (she has gone from 30-40 dives to less than 15 dives per year) because she still wants to dive with nitrox and not use air.

Wouldn't it just make sense to... dive on air? Even if it means longer surface intervals and/or shorter dives? If she is truly experiencing pulmonary toxicity symptoms when diving nitrox she could be causing permanent lung damage.

 

[gamon]

The analogy comparing trimix use in recreational diving to parachutes on airliners overlooks a critical distinction. Parachutes address extremely rare, high-consequence failures in the safest industry in existence, while gas density, narcosis, and CO₂ retention affect every diver on every deep dive.

Only if there are verifiable and permanent consequences.

 

[bardass]

Is she a smoker?

nope
never

 

[crofrog]

nope
never

I was interested because of I've heard of smoking contributing pulmonary O2 tox, what you described was very similar to what I felt when I started having pulmonary o2 symptoms.

It's crazy how much individual variability there is in all of this.

 

[crofrog]

Only if there are verifiable and permanent consequences.

what?

 

[gamon]

@bardass

I can't find a single reference to a person experiencing symptoms such as the ones you describe with this lady, anywhere.

Some sort of odd placebo effect simply cannot be ruled out.

I suggest you do the following:

1- double blind study where the lady in question alternately dives a few tanks of air and a few tanks of nitrox, and reports her symptoms to a person who records them, that same person does not know which tank holds which blend.

2- In the event there is a definite statistical correlation to back up her claims the next step would be to have her dive a 22% blend, increasing the 02 percentage over a series of dives to determine at what level the symptoms begin, again doing this as a "double blind" study with the lady diver and the person recording any symptoms not knowing what she's actually breathing.

That way you can not only verify that her claims are real and valid but also determine at what level she can enjoy the benefits of nitrox without experiencing symptoms. I'm sort of surprised that a trimix and nitrox instructor wouldn't have thought of that.