Hi all, got a question for anyone who knows something about hyperventilating. My mc is in a dark tunnel with another character - both are crawling on their bellies because it's a real small tunnel. Several rats appear scaring the hell out of the mc ( whose never crawled through a tunnel this small in the dark ), he starts to panic and hyperventilate. What can the other character do with no paper bag available? Would breathing into his mouth work ( I heard it has something to do with carbon monoxide? Or maybe I heard wrong). And if the mc doesn't stop hyperventilating would he pass out and for how long?