A number of home nebuliser users in Salford have reported that they have consistently observed a yellow or orange colour in the flame of gas fires or gas cooking hobs if a nebuliser was used in the same room as the gas burning device. To investigate this phenomenon, we used a standard jet nebuliser to nebulise 2.5 ml of 0.9% saline close to a butane-propane gas flame. The flame turned from a pale blue colour to a bright orange-yellow colour within seconds of starting the nebuliser, even if the device was 2 metres or more away from the gas flame (fig 1). The flame remained coloured for at least 10 …