Ever used a canned oxygen Inhaler

[RedinTexas]

I didn't, but my mother did. It was worthless, but she had a problem that needed medical attention.

ETA - I flew for years in the Air Force and if you're going up to altitudes below 10,000 feet, you should be ok unless you have a medical condition. Above 10,000 feet gets tricky. If you go higher and encounter breathing problems a can like that is unlikely to help for long and unless you can get down below 10,000 feet fairly quickly, it won't be of much use. However, if you're thinking of using it due to medical issues, you definitely should consult a doctor first.