Propane is a clean burning fuel. It emits virtually no soot and low carbon monoxide, hydrocarbons and oxides of nitrogen, (otherwise known as smog). Propane emits less carbon monoxide than oil, natural gas, butane, coal, kerosene, and gasoline.
Propane doesn't produce particulates (soot) or noxious gases, which makes it a safe fuel for those with respiratory ailments.
Propane also burns hotter than other fuels. This means you need less fuel for the same amount of energy.