As a well controlled asthmatic on one inhaler,
I know hes not being very subtle, but I think that BSousa is probably correct in his reasons for problems, ie that the cabin is maintained at an altitude of 6-8 thousand feet, and that passengers may not be in the best of health before they board.
Most poeple are not aware of the pressurisation being at an altitude like this, and I guess if you were to go up Mont Blanc in the alps, that you would have similar problems.
Regards, SD..