When a fire occurs, the resulting damage can be classified into two main categories: primary and secondary. Primary damage is the direct result of the fire, such as burning, warping, and melting. Secondary damage, on the other hand, stems from smoke and corrosive substances produced by the fire.
We have extensive experience in analysing both primary and secondary fire damage. In cases of suspected arson, it's crucial to investigate the cause and test for potential accelerants. We collect exhibits from the site, sealing them in nylon bags for analysis. These exhibits can range from burnt furniture to charred rubbish. Our highly trained experts use Gas Chromatography Mass Spectrometry (GC-MS) to analyse the gases emitted by these exhibits. This allows us to detect trace levels of accelerants, such as petrol and kerosene, and differentiate them from pyrolysis products resulting from the burning of plastics.
Secondary damage, unlike primary damage, can be hidden and not easily visible. This type of damage involves the release of toxic and corrosive chemicals. Sampling for secondary damage is typically carried out with swabs and we provide full sampling kits to facilitate this process.
One of the main corrosive substances produced by a fire is hydrochloric acid. Chlorine gas, released from the combustion of chlorinated plastics and rubbers like Polyvinyl Chloride (PVC), combines with moisture in the air to form hydrochloric acid. This acid can condense onto metal components and cause corrosion. By analysing swabs through water extraction and Ion Chromatography, we can quantify chloride levels and determine potential issues, mapping contamination levels around the premises.
Smoke damage can cause surface staining and soot can carry toxic materials associated with burning organic matter. We take samples from fire-damaged areas to establish baseline contamination levels and then swab areas both near and far from the fire. Our scientists analyse these swabs for combustion products, including Polycyclic Aromatic Hydrocarbons (PAHs), Per- and polyfluoroalkyl substances (PFAS), Hexabromocyclododecane (HBCDD), Polybrominated Diphenyl Ethers (PBDEs), and toxic metals. These substances are a mix of combustion products, stain repellents, and flame retardants. PAH analysis is used both as a marker for soot presence and to monitor for toxic and carcinogenic PAHs. The Grenfell Tower fire is a notable example where such chemicals contaminated the surrounding area.
Compounds such as guaiacol and syringol, present in wood smoke from lignin pyrolysis, and levoglucosan and levoglucosenone, pyrolytic products of cellulose and starch, serve as biomass burning tracers. These tracers help map the travel path of fire fumes.
Our ability to offer comprehensive primary and secondary fire damage analysis places us in a unique position. We assist in investigating the fire's source, tracing corrosive and toxic chemicals released, and determining the extent of contamination in the surrounding area, even when physical damage isn't apparent.
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