In use, the hot air from the respirator is known to be unpleasant to breathe and careful training is needed to reinforce the need to keep breathing through it, not to breathe cold untreated air from around it – the hotter the respirator exhaust, the higher the carbon monoxide concentration and the more dangerous it would be to breathe otherwise. Exhaled air also passes through the respirator mouthpiece and an exhaust valve, but not the catalyst, as damp exhaled air would affect its efficiency.
In use, the hot air from the respirator is unpleasant to inhale; proper training is necessary to ensure breathing through it rather than cold untreated air around it. The hotter the respirator's exhaust, the higher the carbon monoxide concentration and the more dangerous it becomes to breathe otherwise. Exhaled air passes through the mouthpiece and exhaust valve but not the catalyst, as damp exhaled air could affect its efficiency.