It is for all airlines, but do note that in order for something to be considered a medical bag (thus, not part of the carry-on limit), it must have ONLY medical-related items in it. In other words, if you have a bag with your nebulizer and your iPad (which you have no medical need for) in it, that bag is not a medical bag and will count towards your carry-on limit. However, if you need that iPad in order to communicate using one of those picture apps or text-to-speech app, that's a medical item so the bag would be a medical bag. If you have a bag with just your nebulizer and medications/inhaler/etc., that is a medical bag and is not counted towards your carry-on limit.