AbstractThis paper examines the influence of oxygen and environmental temperature on the generation of smoke from burning polystyrene sheet. The experimentation was performed using a Stanton Redcroft HFTA linked to a Stanton Redcroft FTB Smoke Box. The results showed that different forms of smoke were formed depending upon the environmental conditions. For example, in oxygen‐enriched atmospheres and at elevated environmental temperatures, as in spacecraft fires, large smoke particles were formed with a lower level of obscuration. This phenomenon was accompanied by higher rates of burn and high fire temperatures. At lower oxygen contents, as in real‐life fire conditions, close to the Critical Oxygen Index, finer smoke particles were formed which gave a higher level of obscuration. The time to maximum obscuration was comparatively l