The main role of the sensor is ''the prevention is better than cure'' like to detect the toxic gases before its lower toxic (explosive) limits. To prevent the damage caused by atmospheric pollution, a monitoring and controlling systems are needed that can rapidly and reliably detect and quantify pollution sources within the range of the regulating standard values. Heterojunction gas sensor is attractive because it overcomes all drawbacks of metal oxides based gas sensors. This works is related to room temperature detection of LPG leakage and thus prevents the accidents.