Note from a toxicologist:
The practice of huffing "Duster" can be extremely dangerous or fatal. The intentional inhalation of 1,1-difluoroethane caused a fatal cardiac arrhythmia in a 42 year-old man Avella, 2006. Several reports of fatal car crashes have been linked to drivers huffing 1,1-difluoroethane.
Both tetra and difluoroethane are active compounds that interfere with brain function and can cause lifethreatening disruption of the heart beat, even in very young users. These are more than just canned air and the danger is more than just asphyxiation.