This was a mis-application of a rule that applies to breathing devices, such as the "Scott air-pac", and such. I hope you were not issued a formal citation. It sounds like you were trying to do 'the right thing.'
Your defense is to show that you complied with the manufacturers' instructions, and that the equipment was appropriate for the hazard.
OSHA leans very heavily toward "training" and "documentation" citations- they're so much easier to issue! And, when there's an injury (or complaint), there is a real desire to generate paper as a way to show the "did their job."
I was on a job where a guy got very- and I mean very- badly cut by a piece of sheet metal. I was frankly amazed he made it across the plant without dying first. The next day, when the inspectors came, there was still the blood trail- looked like a painted line- wherever he had gone. As you might guess, this got the foreman in a bit of trouble.
As soon as the inspectors left, we had a "safety meeting." The new rule: If you get cut- DON'T BLEED ON THE FLOOR! Yes, he was serious- but we couldn't keep from laughing anyway!