Certain exemptions apply for carry-on baggage, such as compressed gas cylinders for medical use or as part of a self-inflating life jacket. Your air carrier may agree to transport compressed gases for non-medical use (e.g. paintball cylinders/guns, scuba tanks, self-inflating life jacket), in checked baggage only, provided certain conditions are met.
CATSA encourages all passengers to arrive at their departing airport well in advance of their flight. Many airlines advise passengers to arrive two hours in advance for domestic flights and three hours in advance for US and international flights.