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A large number of investigations have been reported on minimising the PAH and PCDD/F yields during controlled combustion, such as incineration. This study is an attempt to quantify acute and chronic toxicants including PAH and PCDD/F in conditions relating to unwanted fires. This paper investigates distribution patterns of fire effluents between gas and aerosol phase, and the different particle size-ranges produced under different fire conditions. PVC carpet was selected as the fuel as a precursor for both PAH and PCDD/F. In order to generate fire effluents under controlled fire conditions, the steady-state tube furnace, was chosen as the physical fire model. Fire scenarios included oxidative pyrolysis, well-ventilated and under-ventilated fires. Fire effluent measurements included: carbon monoxide, carbon dioxide, hydrogen chloride, polycyclic aromatic hydrocarbons, chlorinated dibenzo-dioxins and furans and soot. The distribution patterns between gas and particle phase, and the size-ranges of the particles produced in these fires together with their chemical composition is also reported. Significant quantities of respirable submicron particles were detected, together with a range of PAHs. Lower levels of halogenated dioxins were detected in the fire residue compared with those found in other studies. Nevertheless, the findings do have implications for the health and safety of fire and rescue personnel, fire investigators, and other individuals exposed to the residue from unwanted fires.

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This study presents an investigation into the gas phase thermal decomposition of captafol, a sulfenimide fungicide which consists of a thiotetrachloroethyl (-SCCl 2 CHCl 2 ) group bonded to a tetrahydrophthalimide (C 6 H 8 (CO) 2 N-) moiety. The experiments were performed on a bench type apparatus, under conditions representing both under and well-ventilated non-flaming fires. The analyses of gaseous species relied on Fourier transform infra-red spectroscopy (FTIR) and micro gas chromatography (µGC), resulting in the identification and quantification of 11 gaseous products; among them, phosgene, thiophosgene and hydrogen cyanide. Gas chromatography -quadrupole mass spectrometry (GC-QMS) was employed to analyse the condensed products and volatile organic compounds (VOC), while a GC equipped with an ion trap mass spectrometer (GC-ITMS) was used to quantify polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F). The GC-QMS analysis determined several VOC toxicants; viz., trichloroethylene, tetrachloroethylene, benzonitrile and chlorinated benzenes. At higher temperature (600 °C), the oxidation of captafol led to the formation of mono-to hepta-CDD/F congeners including the most toxic 2,3,7,8-TCDD. In addition, the experimental results were compared to those of the other two sulfenimide fungicides, captan and folpet, both of which contain the thiotrichloromethyl (-SCCl 3 ) moiety rather than the thiotetrachloroethyl group of captafol. It appears that the thiotetrachloroethyl group in captafol is responsible for the difference in the toxic pollutants formed, particularly influencing the distribution and yields of PCDD/F congeners. Combined with quantum chemical calculations, the results presented in this article provide an insightful understanding of fire chemistry of the sulfenimide fungicides, especially the pathways to the formation of major toxicants during the oxidative thermal decomposition of captafol.