How does voluntarily holding one's breath work?

Question

The rules for suffocation read as follows (emphasis mine):

Suffocation

A character who has no air to breathe can hold her breath for 2 rounds per point of Constitution. [...] After this period of time, the character must make a DC 10 Constitution check in order to continue holding her breath. The check must be repeated each round, with the DC increasing by +1 for each previous success.

When the character fails one of these Constitution checks, she begins to suffocate. In the first round, she falls unconscious (0 hit points). In the following round, she drops to –1 hit points and is dying. In the third round, she suffocates.

These rules are clear for when a character simply has no air to breath, such as while being strangled or underwater. But what about a character choosing to hold their breath?

For example, a PC enters a room with an airborne poison and begins to hold his breath. After the number of rounds he can safely hold his breath expires, he begins to make the requisite Constitution checks.

What happens on the character's first failed save? Does he...

• ...fall unconscious and continue to suffocate, not breathing?
• ...fall unconscious and begin to breath, no longer suffocating but inhaling the poison?
• ...remain conscious but breath involuntarily, inhaling the poison?

Answer 1

Fortunately there are rules for this in the inhaled poisons section:

A creature can attempt to hold its breath while inside the area to avoid inhaling the toxin. A creature holding its breath receives a 50% chance of not having to make a Fortitude save each round. See the rules for holding your breath and suffocation. If a creature is holding its breath and fails the constitution check to continue doing so, rather than suffocating it begins to breathe normally again (and is subject to the effects of the inhaled poison if still in the area).

So per RAW, it is option 3 (with the caveat that there is still a 50% chance of being affected by the poison every round).

Answer 2

Well ... in real life you can hold your breath until you pass out, so I would say that's the point of "falling unconscious". BUT once you're unconscious you start to breathe again.

I would think this is one of those cases where you should let RL be your guide, which means option 2 "...fall unconscious and begin to breathe, no longer suffocating but inhaling the poison".

Answer 3

I know this is the worst answer to any rules question, but it's really up to the GM. From a RAW perspective, it doesn't seem like there are rules for holding your breath voluntarily (ie: to avoid airborne toxins)

Without contradicting the existing rules, I think the best you could do would be to go with B - they fall unconscious and begin to breathe, no longer suffocating but inhaling the poison. Breathing is normally automatic, so it should resume when a character goes unconscious unless there is something to prevent it--such as a lack of air.

It's not a perfect solution, but the rules give us no way to model situations where the character fails to keep holding their breath before they fall unconscious.

As a better (but less official) option, I would say that the existing rules on suffocation show how long a character can go without breathing, and add another save to determine how long they can actually hold their breath.

Personally, I'd make it a Will save as holding your breath is more a matter of mentally overriding your body, but ymmv. In any event, you'd probably want to give this save a higher DC as people are rarely able to hold their breath until they pass out.