Fire protection water spray systems are prone to blockages which can make them less effective in a fire situation. Testing these sytems with water is unpopular with operators since it can cause major interference with plant operations. A number of candidate dry test methods have been considered in the present study. Following these considerations and a demonstration of the use of a mist-based system, it was decided to develop this method further. The work included mathematical modelling of mist losses during pipe flow confirmed by laboratory tests. An investigation of the effect of partial blockage of mist emission and the determination of minimum mist density to ensure acceptable visibility was also carried out. Mice were exposed to pure toxic gases which are commonly generated in fire incidents, such as CO, HCl, HCN etc., both as single gases and in mixtures. Acute toxicities for 5 to 30 minutes exposures of these gases at various concentrations were examined using such indices as incapacitation time and apnoea time.