Propane is a fossil fuel.
Commonly called LP (Liquid Propane), propane (C3H8) is a non-renewable energy source. Once used or released into the atmosphere, it's gone.
Propane can leak.
If a tank valve is left open while still connected to a device, propane can leak from faulty hoses, burner controls or other equipment.
Propane is heavier than air.
It can pool in low or enclosed areas such as inside your grill cabinet.
Propane is flammable.
The leading cause of propane related fires at home involve grills, hibachi and barbeques.