AbstractThe performance of zine oxide gas large‐scale experiments in an experimental underground mine roadway has been investigated. The sensors were in a simple prototype instrument and the response to products evolved from heated coal wood and PVC conveyor belt was determined. The response was measured as a function of sensor distancef from the combustion products, the ventilation rate in the roadway and the mass of coal dust used. Limited analuysis of the roadway air was also carried out. The results are compared with those obtained in laboratory studies1and suggest that the sensors respond mainly to inorganic gases, e.g. CO, H2, H2S, HCl, and in the case of wood, acetic vapour at concentrations of about 1ppm. The experiments confirm the potential of the sensors as a means of detecting heating involving coal, wood and PVC conveyor bel