Experiments have been conducted in the NFPA 269 / ASTM E1678 radiant apparatus to determine the sensitivity of toxic gas generation to atmospheric oxygen availability and to the conformation of the test specimen. CO and HCN generation can be dependent on the conformation of the test specimen. Thus, it is important that the test specimen exposure to the radiant source adhere to the likely real-fire exposure of the finished goods. Reducing the initial oxygen volume fraction in the apparatus can affect CO and HCN generation, but does not appear to affect the HCl generation. Fitting the bench-scale test conditions to the full-scale fire ventilation conditions is likely to be important in obtaining good correlations of toxic gas generation.