Air quality and testing while travelling

I have been thinking about this lately as winter is coming up in Canada and the possibility of going to a warmer climate for diving this winter is here. A bunch of us were reviewing a series of coroner's reports on diving deaths and many of them report the Heart Attack as the cause of death. Unfortunately, many police agencies do not test for CO upon arriving at a diving death scene and by the time you get to the autopsy, it is impossible to determine if the death was CO related. A friend of mine was diving in Roatan last year and used a Draeger tube to test for humidity in the tank air. He determined that there was too much humidity in the air and that as a result the CO filters would not work. When he advised the resort of this, they emptied all the tanks and replaced the filters and they were fine. However two boats had already left the resort and the divers on those boats were seriously sick all week and could not dive due to bad gas. I guess they were lucky and could have just as easily died.
So the point of all of this is that since DIR diving is all about safety, redundancy etc. I have not read anything about checking breathing gas for purity. What do people do to check that their air is safe ? Has anyone ever used Draeger tubes or do you use a CO analyzer ?

thanks

Christian L.
Gatineau, Quebec
CANADA