Landfills in the U.S. are a major source of methane emissions. A study looked at the environmental impact of a typical U.S. landfill, focusing on gas collection and control. The materials used in building and operating landfills have the biggest impact on toxicity. Methane emissions from landfills contribute significantly to global warming. Stricter regulations on gas collection can reduce methane emissions by up to 52%. It's more effective to collect gas for a longer period than to start collecting it earlier.