PHMSA has become aware of instances where marked and unmarked cylinders have being taken to recycling facilities for disposal while still containing compressed gases and other hazardous materials. Cylinders that have not been purged of their contents can pose a serious risk to health and safety. In the event of a catastrophic failure, the sudden release of compressed gas could cause the cylinder to expel shrapnel or become a projectile, resulting in extensive property damage, serious injury, or even death. Any cylinder still containing material should be considered hazardous. Cylinders are pressure vessels intended to hold compressed gases, and present two serious hazards – the pressurized cylinder itself, which has explosive potential, and the materials being stored within, which may be poisonous or flammable.