I've been slogging thru indonesia for a few months now, diving and spearing. Between water times I'm pretty consistently confronted with a fair bit of pollution and second hand cig smoke(Indo and Acheh in particular are home to some of the heaviest smokers I've ever met-its remarkable). I am admittedly a zealot/psychosomatic (I hope!!) with re: to both and while this is likely a foolish questiion I'm wondering how long it takes to purge CO from your system. I know it binds with RBC about 4x as readily as O2-so how long does it take to clear it out? How hard does the second hand ciggs effect-I try really hard to hold my breath between clouds...I know this is vague, if someone could at least address the CO aspect, thanks--pollution and cigs are such a drag!!