705.40 - Passenger and Cabin Safety Procedures
(1) An air operator shall establish procedures to ensure that...
(d)seats located at emergency exits and seats that are not located on the main deck of an aircraft are not occupied by passengers whose presence in those seats could adversely affect the safety of passengers or crew members during an emergency evacuation.
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Advisory Circular (AC) No. 700-014 - Passenger Seating Requirements and Accessible Air Transportation
4. A passenger’s presence would be considered to adversely affect the safety of passengers and crew members during an emergency evacuation where he or she does not meet the following criteria. Passengers seated at emergency exits:
a. Must be physically capable of using the exit;
b. Must be capable of understanding the printed and spoken emergency instructions;
c. Must be able to visually determine if the exit is safe to open;
d. Must have sufficient mobility, strength and dexterity to reach, operate and stow (or otherwise dispose of) the emergency exit;
e. Must be able to receive aural information from the crew and to orally communicate that information to other passengers;
f. Must be of a minimum age (as established by the air operator) to ensure that he/she has the physical, cognitive and sensory capacity to operate an emergency exit;
g. Must not be responsible for another person as this can hinder the opening of the emergency exit;
h. Must not be travelling with a service animal; and
i. Must not have a condition that might cause them harm by opening the exit.