Life cycle assessment (LCA) studies aim to assess the overall environmental impact (energy and resource consumption, pollutant emissions) throughout the life of a product or service, with the aim of comparing different production options or materials. However, the standard LCA method excludes the impact of accidents, such as fires or accidental pollution incidents. In the case of the assessment of flame retardants (FR), used specifically to prevent and reduce the impact of accidental fires, it becomes essential to take the impact of accidental fires into account.
The objective of this study is thus to compare the overall environmental impact of using or not using flame retardants in domestic upholstered furniture, taking account in the Life Cycle Assessment the impact of accidental fires. This was based on a previously developed methodology (the “Fire-LCA” model), and previous experience of Fire-LCAs carried out for TV sets and electrical cables.
Fire statistics from the UK were used to assess the changes in the number and extent of fires resulting from a move to fire resistant furniture. The UK introduced in 1988 Furniture Fire Safety Regulations requiring domestic upholstered furniture to resist ignition by a small flame, whereas previously in the UK, and still today in the rest of Europe, furniture is only resistant to ignition by a smouldering cigarette and can be readily ignited using a small lighter (see photos pages on the inside of the back cover). Analysis of UK fire statistics trends prior to these Regulations, and from 1988 to 2000, enabled a robust statistical model to be developed, with results being little affected by the scenarios used.
Data were gathered on furniture production for the sofa model studied, and for end-of-life disposal (with and without flame retardants) to provide LCA input data for all phases of furniture life from the cradle to the grave. The pollutant emissions from accidental fires, of different gravity (extent of fire), involving flame retarded or non flame retarded furniture were obtained using full scale fire tests on both commercial sofas and on fully furnished test rooms at the SP fire test facilities, Borås, Sweden. A non-flame retarded sofa was used to represent the mainland Europe market and two different (commonly used) flame retardant procedures were used to represent the UK market.
The furniture manufacture phase was the principal source of energy consumption and emissions of CO2, NOx, carbon monoxide, were similar for the flame retarded (FR) and non-FR furniture. Accidental fires, however, were responsible for a significant portion of the emissions of hydrogen cyanide, polycyclic aromatic hydrocarbons and TCDD/TBDD-equivalent (dioxin/furan equivalents).
Calculated total sofa life cycle TCDD/TBDD-equivalent emissions were higher for the flame retarded sofas, both due to emissions calculated for end-of-life incineration (hypothesis: 30% of sofas go to domestic waste incinerators) and emissions from the few fires containing these sofas. The estimate of emissions from incineration assumed that they are proportional to input Cl/Br levels, which will lead to a somewhat conservative emission estimate (i.e., overestimated).
In contrast, the total polycyclic aromatic hydrocarbon (PAH) emissions were higher for the non- FR sofas, because of the higher frequency and gravity of accidental fires. A comparison between the relative importance of PAH and dioxin and furan emissions using a modified cancer risk model clearly shows that the level of PAH emissions is of far greater significance than that of dioxins and furans. Thus, based on PAH emissions the environmental risk associated with flame retarding a sofa is outweighed by the impact of fire emissions associated with non-flame retarded sofas.
Further, the total sofa TCDD emissions calculated for the worst-case over the whole life cycle (manufacture, accidental fires, disposal) correspond to approx. 0.003% of total annual TCDD emissions from all sources. Similar data is not available for TBDD-equivalent emission or PAH emissions, but one should note that PAH emission from the whole life cycle of one million sofas correspond to, at worst (i.e., for the non-FR case), less than 1% of PAH emissions expected only from fires in Sweden each year.