Propane at room temperature is a colourless gas. Odourless when pure, it is invariably mixed with other hydrocarbon gases (e.g. with butane in LPG) and sulfur-containing odourants to render it detectable by smell. It is highly flammable with an ignition temperature of 450°C.
Propane is mildly anaesthetic and slightly irritating to the mucous membranes but its main hazards are its flammability and the risk of oxygen displacement if a large enough volume leaks into a confined space.
Propane occurs in natural gas and is a component of LPG (liquid petroleum gas) used for domestic heating and cooking.