Canadian Underwriter

Challenges in Fire Damage Assessment and Remediation: Forensic Engineering Perspectives

May 17, 2016   by Kirsten Hoedlmoser, Chemical and Environmental Engineer and Intermediate Associate, Giffin Koerth Forensic Engineering and Science

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Fires are one of the most common causes of property damage. Even with modern advances in fire detection and protection, fires remain commonplace and can cause hundreds of thousands of dollars of damage. Within Ontario in 2013 alone, over 7,000 fires involving structures occurred, with the estimated losses totalling over $570 million. The impacts of fires extend beyond building damage; modern remediation professionals increasingly recognize the assessment challenges and hazards posed to both occupants and contents exposed to fire and smoke contaminants.

From the perspective of an Environmental Engineer, the first step in remediating fire damage involves assessing and delineating the extent of the loss-related damage-but what do we do when the impacts are not always visible to the naked eye or when the impacts overlap with background levels? One might think that, much like asbestos, accepted guidelines or regulations would be in place to help navigate the assessment and remediation process.

Kirsten Hoedlmoser, Chemical and Environmental Engineer and Intermediate Associate, Giffin Koerth Forensic Engineering and Science

Kirsten Hoedlmoser, Chemical and Environmental Engineer and Intermediate Associate, Giffin Koerth Forensic Engineering and Science

Unfortunately, this is not the case for potentially hazardous fire residues. While high-level guidelines exist for fire restoration, these guidelines are generally geared towards managing expectations during the process and providing basic cleaning guidance to contractors. How, then, can the environmental aspects of a fire claim be best managed in the absence of universally accepted best practices?

Depending on the source, extent of combustion, and the nature of the materials impacted by a fire, myriad different chemical contaminants and residues can be released throughout a building or absorbed into porous contents. Contaminant residues can include soot, char, ash, and polycyclic aromatic hydrocarbons (PAHs).

Soot, char, and ash are common combustion by-product residues that can be detected via microscopy on wipe samples collected from impacted surfaces. Soot consists of carbon-based and inorganic solids in conjunction with organic tars and resins, less than one micron in size. Char is particulate produced via incomplete combustion and is larger than one micron. Char can contain some of the original material’s structure, minerals, etc. Ash, in contrast to char, is the residue remaining after complete carbonization of the material. Ash does not maintain its original form.

Combustion by-products commonly contain carcinogens, including those present in PAHs, a group of chemicals generated or released during combustion. PAHs condense onto building surfaces after a fire, just as water vapour condenses onto a cold windowpane. Because motor vehicle emissions, cooking activities, and indoor heating sources can also produce PAHs, background concentrations can reasonably be expected to be present within indoor spaces. Proper determination of background levels is important.

As detailed above, fire events can release or produce several hazardous contaminant substances that adversely impact indoor environments, adding to the challenge of returning a fire-impacted building to a state where it can be re-occupied. Assessing the presence and extent of residual contaminants (whether airborne, adhered to building finishes, or absorbed into contents) and interpreting site assessment data to guide remediation is a complex task.

First, there is a lack of guidelines and regulations specific to fire and smoke contaminant residues. In Ontario, certain PAH species have airborne exposure limits set by Ontario Regulation 833 (O.Reg. 833), “Control of Exposure to Biological or Chemical Agents”. These airborne regulatory limits, however, do not speak to the concentrations of soot, ash, and/or char that are acceptable on interior building surfaces.

Using only PAH analysis to assess fire residues can be costly and sometimes misleading due to the presence of background concentration levels. Other fire remediation and restoration guidelines provide only a general overview of the fire damage remediation and restoration process, without providing guidelines and recommendations regarding appropriate sampling and analytical methods, or acceptable residual fire contaminant concentrations.

The determination of safe levels of fire residue concentrations, particularly physical deposits like soot and char, often remain open to interpretation regarding the ‘acceptable background levels’ versus the levels that pose issues from an occupant health and safety perspective. A qualified environmental professional should be relied upon for interpretation of such fire residue concentration data, with the end objective of returning the building to its pre-loss condition. This logical approach ensures that insurance claims do not include background concentration levels in the restoration scope, and prevents attempting to clean industrial manufacturing buildings where smoke may be continuously generated through hot processes on assembly lines or other procedures.

Commonly used ‘presence/absence’ types of assessment methods-such as chemically-treated sponges wiped on walls to visually confirm the presence of smoke impacts-do not effectively identify trace level smoke contaminants such as char or soot. As well, these methods are easily confounded by high background dust and dirt levels on surfaces. While these visual field tools are helpful for the initial delineation of gross soot and char residues during the emergency phase, these assessment methods should not take the place of more accurate data collection and third-party analytical methods (i.e., surface swab sampling for soot, char, and ash residues and/or PAH concentrations). Third-party laboratory results provide the proper basis for further forensic expert review and can act as evidence in disputes and litigation that may arise.

An appropriately-accredited laboratory should be used for the analysis of surface wipe sampling, whether for soot, char and/or ash, PAHs, or other residues of concern. The laboratory should use an analytical method directly applicable to fire contaminants (e.g., ASTM D6602-13). Unfortunately, Canada has a shortage of laboratories that can properly perform this analysis. In our view, it is not appropriate for laboratories to attempt such specialized microscopy simply because they do other types of environmental analytics.

The possibility of fire residues being present within building cavities (i.e., not only on visible finishes) should also be appropriately investigated, as pressurization of smoke and gases within a building can force fire contaminants into voids. Frequently, only visible surfaces and finishes are cleaned, while hidden areas are not appropriately assessed or remediated. These concealed contaminants generally later manifest in the form of smoke odours that reappear post-restoration as the residual contaminants volatilize and subsequently enter the airspace of the building.

The presence of hazardous materials, such as asbestos and lead, should also be assessed before disturbance of fire debris and demolition of fire-impacted finishes. In developing the appropriate remedial scope of work, environmental professionals must identify the applicable regulatory requirements by provincial jurisdiction. While many provinces have rigorous asbestos testing and abatement requirements, lead is less clearly regulated as it relates to restoration activities, and remediation is often mismanaged by restoration professionals. Both the Ontario Ministry of Labour (MOL) and the Environmental Abatement Council of Ontario (EACO) have developed lead abatement guidelines in which various classes of operations and engineering controls are detailed for projects involving lead-containing substances. When combined, the nature of fire contaminants, the absence of a clear and consistent set of guidelines or formal regulatory framework, and the scarcity of proper analytical resources pose a significant challenge to professionals assessing the environmental impacts of fires. These challenges, when not appropriately managed, can result in assessment and remediation delays, inadequate remediation efforts, and exposure of building occupants and restoration personnel to hazardous materials and carcinogenic fire residues. The increased awareness among members of the public regarding environmental and chemical exposure and resultant health effects may also serve to increase the frequency of claim and legal disputes arising from fire losses.

Consideration of the above will help to ensure that fire damage assessments and remediation projects run smoothly, with reduced health and safety risks for all individuals involved. It is our view that the relevant methodologies, analytical methods, clearance standards, and remedial practices require refinement in order to provide a consistent, safe approach to the restoration of fire losses. We anticipate that residual fire contaminants will become a more prevalent concern in the coming years, and we look forward to contributing to the growing body of knowledge.


Kirsten Hoedlmoser, P.Eng., is a Chemical and Environmental Engineer and Intermediate Associate with Giffin Koerth Forensic Engineering and Science. She has provided consulting engineering support to the assessment and remediation of numerous fire losses.

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