Here are the answers to your questions: 1. Gases are formed from landfills as waste decomposes anaerobically (without oxygen). This process produces methane, carbon dioxide and other gases. 2. The most common type of landfill in the US is a municipal solid waste landfill, which accepts household trash and some hazardous wastes from sources like businesses and institutions. 3. Yes, landfill gas can be hazardous if it migrates off-site from the landfill. The main gases of concern are methane and volatile organic compounds (VOCs). If inhaled, these gases can cause headaches or dizziness. If the gases accumulate in enclosed spaces, they can displace oxygen and cause asphy