re: re:Thanks for the info podrock.
Oh, and above 45,000' in order to breath air- you need a pressure suit/spacesuit. On Mt Everest 29,000' you can still breath air and can enrich our oxygen intake by breathing pure Oxygen. So from 29,000 to 45,000' you can breath from an oxygen mask- it become harder to do this as you approach 45,000'.