Posted By Ron Hunter There isn't a problem.The low capacity of the bottle doesn't come within Carriage Regulations limits, and strictly speaking, probably doesn't come within the definition of 'carraige'. Any passenger could come on to your bus with pressurised containers as hand luggage- would you worry about that? Only real issue is to prohibit smoking, and in the unlikely event vehicle was on fire with oxygen bottle left in it, to inform the fire brigade! There is an obvious temptation also to answer your question 'where do I stand' with the cheeky answer: Only on the lower deck, and only to the number limit posted on the capacity notice! (Sorry) ;-)