Building fires produce an array of Combustion By-Products (CBP). Nearly all fires produce char, ash or soots in varying amounts. Char consists of irregular shaped fragments of combusted material that are greater than one micron in size. Ash particles consist of fuel material that has had almost all of the organic material burned away, leaving inorganic remnants that are often crystalline. Soot particles are smaller particles (typically 10 - 50 nm) formed from incompletely combusted, volatile fuel material, and considered a secondary indicator of fire residue. Soot particles may darken the surface of a wipe sample and they can cluster to form agglomerates as large as 1 mm (EMLab P&K; The Environmental Report, M. Berg; Vol 10, Issue 5).
Smoke from a typical house fire contains hundreds of different chemicals and fumes. As a result, damage caused by the smoke can often exceed that caused by the actual heat of the fire. In addition to the physical damage caused by the smoke of a fire – which manifests itself in the form of stains – is the often even harder to eliminate problem of a smoky odor.
These ultra fine particles (char, ash and soot), along with the hundreds of organic chemicals caused by thermal decomposition of plastics, wood, resins and other building materials, infiltrate nearly every open cavity and aperture of the home embedding in insulation, and clinging inside wall cavities, window frames, appliances, mechanical systems, roof assemblies, contents, apparel and furnishings. Cleaning of these building products is rarely 100% effective often resulting in smokey odors and impact persisting for months and even years after the event – despite aggressive efforts such as ozonation and chemical cleaning.
Furthermore, smoke corrosion is often experienced weeks or months after a fire involving plastics, PVC and sulfur-based products since their pyrolysis generates hydrochloric and sulfur acids. Smoke corrosion often causes premature equipment and appliance failures reducing the life expectancy of electronic products and voiding warranties.
“Ghosting” is a phenomenon often occurring in areas where smoke contamination occurs. Soot from the fire migrates throughout the home via thermal currents and ventilation systems agglomerating on drywall surfaces and causing localized darkening. The darkening is often found at wall-ceiling intersections, outlining ceiling joists and highlighting drywall nail heads. Temperature, moisture variances as well as electrostatic charges cause the deposition of soot on these surfaces. Soot may also be mixed with metal oxides, be coated with sulfuric acid, and in the gas phase contain polycyclic aromatic hydrocarbons (PAHs). PAHs are renown mutagens and are classified by the International Agency for Research on Cancer (IARC) as “known human carcinogens” (Wikipedia, Soot; 2016).
Besides CBPs, fires produce hundreds of volatile organic compounds (VOCs) ranging from light weight (formaldehyde, acrolein, acetonitril) to semi-volatiles (acenaphthylene, naphthalene, methylbiphenyl, PAHs). Fire VOC (fVOC) indicators were selected based on their prevalence in multiple types of fire situations, scarcity of other sources, and ease of analytical determination.
Typically, chemical residue from recent fires will include a mix of all of the fire/smoke indicators as well as other chemicals produced during the combustion process. Because of the potential for other sources to impact the results, detection of several fVOCs is necessary to provide a positive result, indicating the presence of fire and smoke residue. As time passes, the more volatile components will dissipate leaving only the heavier compounds. These heavier compounds can also be adsorbed by porous materials in the vicinity of the fire and will be slowly re-emitted, causing the lingering smoky odor characteristic of fires. The detection of the more persistent heavier VOCs and SVOCs suggests that fire and smoke residues remain, and may be perceived as lingering odors or health impacts under certain conditions (Prism Analytical, AN537: Fire VOCs; 2015).
ABF uses state-of-the-art science including microscopic examination, SEM/EDX and GC/MS for analysis of suspect CBP samples. Our comprehensive investigation will identify smoke damaged building materials and furnishings, and develop a protocol for appropriate remediation work. We are able to assist in resolving insurance claim disputes and calmly guide you through the complex process of getting your home restored to pre-loss conditions.