If the waste left there will be a few gas that is caused by fermentation, such as biogas, combustible or explosive gas and H2S (hydrogen sulfide gas), which has a foul smell.
If I leave it garbage information that could have caused the fermentation gases, including methane, which can ignite or explode. And hydrogen sulfide (Hydrogen sulfide), which stinks.
If the garbage information left long have gas resulting from fermentation, biogas, which include a fire or explosion, and hydrogen sulfide. (hydrogen sulfide) malodorous.