I'm going to take us out into a weird utopian bizarro world, but most places you can get nitrox also supply a O2 analyser so those without one can analyse their own tanks. Divers that are properly trained have come to expect this as the norm. It would not take much to have a shop CO analyser that all divers could use to analyse every tank, provided they were properly trained to use the analyser. Divers that are independent or do not trust how well the shop gear is maintained would still be able to purchase their own, just as they do with O2 analysers. Ken, I would even support our local dive community chipping in to offset the costs to the shops, perhaps this is a discussion that would be worth having.