A risk analysis of a pesticide warehouse has been carried out by Riso National Laboratory. The most important risks from the plant were emission of toxic substances released from fires involving large quantities of chemicals, and release of fire-fighting water contaminated with chemical substances. Two areas where more knowledge is required were identified: (i) assessment of environmental effects due to release of ecotoxic substances with the fire-fighting water; and (ii) assessment of the toxicological effects to humans of the fire effluents from a fire involving large amounts of chemical substances. With respect to the latter problem, important research areas are development of methodologies for assessment of the chemical nature and quantitites of the toxic substances that can be generated during the fire course, and also estimation of the effect to humans from inhalation of a complex mixture of fire products. In order to remedy some of the problems, an experimental research project has been initiated, sponsored by the CEC STEP programme. As an example, some results of the work are given in this paper: LC50 values are shown for the combustion atmospheres generated from selected pesticides by the DIN 53 436 furnace. The values are determined by use of an empirical N-gas model.