The evolution and development of industry has caused increment in pollutants and led to considerable attention to gas sensor technology for monitoring environmental pollution especially in refineries. Gas sensing has become progressively more widespread as the use of carbon based fuels and industrial chemicals plays an increasingly significant role in modern living. These developments necessitate the monitoring of various gaseous species including oxygen levels in controlled atmospheres and during combustion processes, flammable gases preventing explosions and fires, and toxic gases and preventing harm to people and the environment.