The selection of a method for the ultimate disposition of the fluid discharged from a relief device is influenced primarily by the nature of the fluid. Innocuous materials such as water or air can be discharged directly to the air or the ground. While flammable gases and vapors may usually be discharged to the atmosphere safely, the environmental impact of such discharge may be unacceptable. Flammable liquids and all toxic substances usually require contained collection, separation, and disposal systems. The following sections briefly describe the options available for the intermediate and final disposition of relief discharges.