Answer:
By release of methane gas
Step-by-step explanation:
Most of the waste in a land fill is biodegradable which releases methane gas in the air while degrading.
Methane gas is a green house gas which is able to entrap the heat radiated back by the earth. Entrapping of heat energy causes rising of global earth temperature thereby causing global warming.
Methane is much dangerous than carbon dioxide as it entraps twenty time more heat radiated by earth.
Hence , in this way solid garbage in landfills can result in air pollution.