http://www.tc.gc.ca/CivilAviation/pu.../RAC/Annex.htm
Use of Oxygen
605.32
(1) Where an aircraft is operated at cabin-pressure-altitudes above 10 000 ft ASL, but not exceeding 13 000 ft ASL, each crew member shall wear an oxygen mask and use supplemental oxygen for any part of the flight at those altitudes that is more than 30 min in duration.
(2) Where an aircraft is operated at cabin-pressure-altitudes above 13 000 ft ASL, each person on board the aircraft shall wear an oxygen mask and use supplemental oxygen for the duration of the flight at those altitudes.
(3) The pilot at the flight controls of an aircraft shall use an oxygen mask if
(a) the aircraft is not equipped with quick-donning oxygen masks and is operated at or above FL250; or
(b) the aircraft is equipped with quick-donning oxygen masks and is operated above FL410.