Propane gas is not toxic. However, should a leak occur, the build-up of propane gas can become dangerous. Because propane is heavier than air, it tends to settle in the lowest available space. Very small amounts of propane are required to create a flammable mixture of gas and air. In the limited space of a recreation vehicle, for example, a propane leak can create a hazardous situation.
Propane requires a large volume of air to burn properly.
In fact, 23.5 cubic feet of air is needed to burn just one cubic foot of propane. With adequate ventilation, an operating burner gives off a number of harmless products such as carbon dioxide and water vapour. But a propane appliance starved of oxygen can quickly produce dangerous amounts of carbon monoxide. For safety s sake, use your propane appliance only for the purpose for which it was designed. Never use an unvented heater, even for temporary heating, in a residence, in any enclosed space, or any place where sleeping accommodation is provided.