Canisters are pre-cleaned evacuated cylinders useful for air sampling. Passivated canisters represent suitable devices for volatile and apolar molecules [49], as suggested by the most used standardized procedure [50]. The principal advantages of their use are that the air sample is collected without any breakthrough and there is no degradation of the trapping materials. Canisters need to be carefully conditioned and pretreated to avoid contamination problems and require complex sampling apparatus. Moreover the container volume is limited to a few liters, unless greater amounts of air samples are collected by means of pressurization, and they are more expensive than polymer bags [51,52]. Canister sampling does not work for dynamic olfactometry; only polymer-based bags are suitable for this use.