Landfill gas monitoring is the process by which gases that are collected or released from landfills are electronically monitored. These gases may be measured as it escapes the landfill (surface monitoring) or as it is collected and redirected to a power plant or flare (collection system monitoring). What is this gas? Landfill gas is a mix of different gases created by microorganisms within landfill. Landfill gas is about 40-60% methane, with the remainder mostly carbon dioxide. Other volatile organic compounds (VOCs) comprise the remainder which might be less than 1%. These trace gases and elements include a large array of species, mainly simple hydrocarbons. Landfill gas and the environment Landfill gases influence climate change. CO2 and methane are both greenhouse gases. For global warming potential, methane is over twenty five times more detrimental than carbon dioxide. Because gases produced by landfills are valuable and hazardous, monitoring techniques are needed. Flame ionisation detectors are used to measure methane as well as total VOC levels. Surface monitoring and sub-surface monitoring, as well as monitoring of the ambient air, is carried out.