Is spell "Miasma" broken (from MotW)?

[Tar-Edhel]

When you're holding your breath, you make saving throws because you can't take in air.

To reset the timer, you'd have to take in air.

By electing to cease to hold your breath to cough for a round, you either don't take in air - in which case your timer doesn't reset - or you do - which is voluntary breathing, and you fall unconscious.

-Hyp.

I'm not so sure about this.

From MotW, p. 91

By filling the subject's mouth and throat with unbreathable gas, you prevent him or her from doing much more than coughing and spitting .

That is indeed the result of the spell. By coughing, you keep your respiratory system clear enough to breathe.

The subject can hold his or her breath for 2 rounds per point ofConstitution but must make a Constitution check (DC 10 +1 per previous success) each round thereafter to continue doing so .

Note that holding your breath is optional.

Failure on any such check (or voluntary resumption of breathing) causes the subject to fall unconscious (0 hp). On the next round, the subject drops to -1 hit points and is dying; on the
third round, he or she suffocates (see Suffocation in Chapter 3 of the DUNGEON MAsTER's Guide) .

So couldn't one interpret that you may simply cough your time under the spell without any other adverse effects?

If you do absolutely need to act, you may hold your breath. But you cannot resume the coughing fit to breathe. If you try, you fall unconscious (voluntary resumption of breathing). A gentle DM (rare but they do exist! ) could even state that the target knows that it must keep coughing if it doesn't want to drown in the miasma.

It is an interpretation but it does make the spell a little more balanced, IMHO.

Waddya guys think?