As we already know, garbage causes many pollution problems and when piles of garbage sitting in one area for years is mixed with different chemicals and weather conditions, it can be fatal to the environment. The biggest gas that comes from landfills that effect the air quality is methane gas. It is greenhouse gas that comes from decomposition and it is very dangerous. According to the Energy Justice Network, "Landfill gas is about 40-60% methane, with the remainder being mostly carbon dioxide (CO2). Landfill gas also contains varying amounts of nitrogen, oxygen, water vapor, sulfur and a hundreds of other contaminants -- most of which are known as "non-methane organic compounds" or NMOCs. Inorganic contaminants like mercury are also known to be present in landfill gas. Sometimes, even radioactive contaminants such as tritium (radioactive hydrogen) have been found in landfill gas" (Mike Ewall). Landfills would be a primary pollutant because the toxic chemicals are hazardous before even mixing with oxygen or any other element. Many chemicals only add to the destruction of the ozone layer that ultimately causes global warming and other environmental problems. Landfills used to be less threatening to the earth and the people living around them, but not that more plastics and toxic materials are being used everyday, it is causing more and more problems once reaching a landfill. The attached picture shows this, they are finding more and more plastic and aluminum products in landfills which take thousands of years to decompose in a landfill.
Ewall, Mike. Primer on Landfill Gas as "Green" Energy, November 2007. http://www.energyjustice.net/lfg