I may be stating the obvious but this is aimed at new scuba folks. Nitrox is a very useful tool under certain conditions but quite dangerous for general use. If you are diving where the max depth is less than the 120-100 ft range [depending of the Nitrox mix] AND YOU CANNOT POSSIBLY GO DEEPER, as already said, it adds BT and shortens SI or it can add a safety factor by using Nitrox with air deco schedules. This is sometimes done by older divers on multi-day, multi-dive days such on a live aboard. This gives the slow tissues a little leeway. I would not allow a diver into the water with Nitrox on a wall dive or say to the topmost part of a deep wreck dive. The danger of accidentally exceeding the max depth is too great. Now I understand that some dive operators do allow this but I still have a problem with it. In addition Nitrox, should be used in dedicated cylinders that are clearly marked with Nitrox and the mixture. While not current on the most recent standard of practice we always required a tank to be completely emptied if changing mixture. We also would do the same with a visual inspection, surface cleaning and valve overhaul when switching tanks to and from air/ nitrox service.
We also did some mixed gas dives [leading edge back then and this was before recreational use of rebreathers] and used O2 for decompression. Lastly, I have observed fill stations operated by untrained operators with poor maintenance practices offering Nitrox. Of course I have seen questionable air stations as well. We had some very expensive gas testing equipment to test our mixtures. Would like to know what this equipment costs these days? Its been awhile since I was active in the industry but I am sure the basics have not changed much. Good diving!
RJ