What compound causes the foul smell when the leakage of LPG takes place?

While leakage in LPG gas cylinder occurs the compound which gives a foul smell is ethyl mercaptan. 
Leakage of LPG can be very harmful and may cause an explosion as LPG is a very good fuel. Therefore, to prevent this, the homeowner or other member of the family should be able to detect the leakage of LPG.

Hence, ethyl mercaptan is added so that a foul smell is detected by the homeowner and fire can be prevented.