This paper describes current studies at the Fire Research Station on the role of smoke and toxic gases in causing injury and death in fires involving polymeric materials used within the structure and contents of buildings. The work involves obscurational studies of smoke, chemical analysis of decomposition and combustion products, pathological studies and, where appropriate, bioassay procedures. Basic details of these studies are presented together with a summary of the work carried out, and conclusions reached, following the fire at the Woolworth's store, Manchester, on 8 May 1979, in which 10 persons lost their lives. This event focused attention in the United Kingdom on the rapid release of smoke and toxic gases from burning furniture and furnishings.