The invention relates to an improved poison resistant pellistor which is particularly useful in resisting the common poisons like sulphur dioxide and chlorine. The invention mainly consists of creating an effective barrier, of filter material like the glass wool impregnated with barium chloride and O-toludine around the active (sensitive) element of the pellistor - to prevent undesirable and harmful sensor poisons like sulphur dioxide and chlorine from reaching the active element. The invention offers a cost effective .and a simple method for tackling the common problem of some of the sensor poisons.
