When the organic matter present in the sanitary landfill decomposes , it generates:

Whenever any organic matter is kept in a sanitary landfill for disposal, it produces methane gas. Methane gas is a dangerous and toxic gas that, if found in the air, can harm the environment and human life. It is also called a greenhouse gas. Methane gas is assembled in some landfill and utilized as fuel, either directly taken or in the form of biogas.