To support the transition away from fluorinated substances used as refrigerants, there must be a workforce that can guarantee the safe handling of alternatives such as natural refrigerants. This section provides for knowledge and training material related to the most common natural refrigerants, e.g., carbon dioxide/CO₂ (R744), hydrocarbons (such as R290 and R600a), and ammonia/NH₃ (R717), as well particular technologies based on these working fluids, such as transcritical CO₂ systems, and low-charge ammonia systems.