For example, testing after a typical residential kitchen fire consists of finding smoke particles by simple observation. Where observation is not conclusive, the adjuster, contractor, or property owner may take wipe samples with a cellular sponge, absorbent paper, or a similar medium. The contrast visible on the wipe or the target surface indicates whether that area requires work. This is not high technology, yet the results of wipe testing are almost universally accepted after building fires.

In another situation, black particles appear with no apparent cause. Are they bacteria, candle smoke, or perhaps tobacco? In this case, the testing must identify the composition of the particles in order to characterize their source. The targets of both tests are particles, but the tests are distinctly different. If the sampling and tests for the two situations were reversed, then neither would provide the answer needed.

All Evidence Should Be Considered

Even though the test of choice may be regarded as precise and definitive, other evidence can affect the result. Visual evidence, other procedures, testimony of observers, and site conditions may modify the original test rationale. Good science requires that all relevant information be considered. Therefore, test results should relate to the real world, not to a narrow slice of information.

The Station Fire

With these considerations out of the way, let's consider the situation in southern California. The Station fire burned out of control for several weeks in the autumn of 2009, consuming tons of trees and vegetation. It was one of the largest fires in California history. Individuals who experienced the forest fire smoke described an atmosphere darkened by smoke, with particles permeating building interiors. To resume normal life, residents began to clean the smoke particles, in some cases enlisting professional help.

Large particles continued to appear long after the fire was extinguished. It became clear that in many homes a single cleaning would not resolve the problem. Some cases report smoke particles are still appearing months after the fire, carried by prevailing winds.

Smoke damage is a covered peril in most homeowners' policies. A multitude of insurers responded to smoke damage claims from the Station fire by covering the cost of remediation, usually calculated as the cost of professionally cleaning the building and contents. However, in some cases the insurer has required testing by a Certified Industrial Hygienist (CIH) to confirm that smoke damage occurred. The sampling and test procedures of some CIHs have consistently found that the percentage of carbon in their samples was below a 1-percent threshold and thus did not qualify as significant damage. The origin of the 1-percent threshold is unclear. Even so, the insurer denies coverage by that evidence.

Does Incursion of Forest Fire Particles Constitute a Loss?

There exists no scientific definition of loss as it relates to buildings or personal property. An assessment of loss requires human interpretation. The loss may be in appearance, utility, value, life expectancy, or similar quality.

In the case of smoke, there is general agreement that combustion particles are usually present in all buildings. This "normal" concentration will vary with the building's location, maintenance, and the activities of its occupants; however, it can usually be established within an order of magnitude by comparison with unaffected sites.

When a claim is filed, the insurer must determine whether a covered loss has occurred. When the claim is one of thousands from a forest fire, the cause is easily established. Determining the extent of the loss may require inspection of the site. Weeks or months may have passed since the fire, and cleaning of the building and contents has probably been performed repeatedly. Under these circumstances, what tests are appropriate? For our purposes, we will refer to these as Tests A through D, as outlined below:

A. One that establishes the current particle level at the site?

B. One that determines the chemical composition of particles in samples taken at the site?

C. A test that relates the quantity of carbon to the quantity of other substances present in the sample?

D. A test that portrays the actual level of combustion particles present at the time of the loss?

Returning to the opening paragraphs, testing should answer relevant questions. In this case, the question is whether an insurable loss occurred and if so, the extent of that loss. With the Station fire, black particles continued to appear afterward, so continual cleaning was performed. Therefore, conditions at the time of the inspection (Test A) are irrelevant. Insurance relates to the conditions immediately following the loss, not weeks or months later.

Most people would agree that a sudden appearance of black particles is not normal and departs unmistakably from the conditions present a day earlier. The particles are clearly visible, they darken impacted surfaces and transfer to hands and clothing. Ingestion of the particles is detrimental to health. Furthermore, smoke particles are potentially corrosive to electronic components, wiring, and decorative metals. So labor and materials must be expended to restore a livable, non-destructive environment.

Is the chemical composition of those black particles relevant? In the absence of an alternative source for the sudden incursion of black particles during a forest fire, how can the source be reasonably questioned? Under those conditions, any reasonable observer would acknowledge the forest fire as the source of the black particles, so the chemical analysis of Test B is irrelevant.

Test C relates the quantity of chemical carbon present in the sample compared to the quantity of other substances contained in the sample, expressed as a percentage. How can the impact of smoke particles relate to other materials that may be present? The quantity, size, and mass of smoke particles present is an absolute quantity, not a dependant variable. If no other materials were present, then those smoke particles would comprise 100 percent of the sample. So if half were present, the same quantity of particles (or carbon) would become 50 percent of the sample. How can the same quantity of smoke particles constitute different percentages? Test C must therefore be considered both immaterial and misleading.

The final choice, Test D, portrays the actual level of combustion particles present at the time of the loss. How can we recreate the smoke particles after repeated cleaning has been performed? It is not necessary to create the particles, only to find them. Every house contains crannies, soffits, and ledges that escape normal cleaning, especially when the occupants are attempting to contain an ongoing problem. If samples are consciously taken from those unobtrusive surfaces, then would they not represent the distribution that occurred at the time of the forest fire?

What Test Methods Are Appropriate?

Thus far, we have avoided naming the various tests to which the sampling techniques are directed because their names are long, complex and intimidating. There is Energy Dispersive X-ray Spectrometry, Polarized Light Microscopy, Epi-reflected Light Microscopy, Transmission Electron Microscopy, and Scanning Electron Microscopy, Gas Chromatography/Mass Spectrometry. Despite their portentous names, these tests can be grouped by function into a few categories: chemical analysis, quantitative analysis, and visual analysis.

With the exception of optical microscopy, these highly sophisticated devices have a single purpose: to identify the composition of a sample and quantify its components. We have already established that combustion particles deposited during an active forest fire render further identification futile, as the cause is obvious. Nevertheless, these tests share another characteristic: they convert the smoke particles into a different physical state, then analyze the modified substance and provide some sort of rating for the various components.

This is analogous to taking a cubic foot of snow, melting it, and analyzing the inch of water that remains. After forest fires, we are concerned with smoke damage, not elemental carbon. Like snow, smoke particles have bulk, yet are extremely light. They travel for miles on air currents. Their significance lies in their appearance and behavior as smoke particles, not as elemental carbon. Ignoring the reality of smoke particles in favor of a sophisticated carbon analysis is disingenuous, especially when it leads to conclusions that ignore reality.

A method of analysis that is frequently overlooked is simple reflected light microscopy. At appropriate magnification of 100X to 200X, a clear image of smoke particles and background materials is immediately available. Particle size and intensity can be optically measured.

What Sampling Methods Are Appropriate?

There are many ways to sample particles. If airborne pollutants are the target, then air samples can be taken with calibrated vacuum pumps and collected on a filter. If the chemical composition of particles is the target, then wipe samples or vacuum samples may be taken. Wipe samples collect materials by moving a collection medium across the target surface. This collection method destroys the original form of the particles when the medium is flushed with a solvent and made suitable for the testing device.

A lift sample consists of a section of clear sticky tape which is pressed onto a target surface then lifted and adhered to a glass slide or other medium. The lift sample retains the smoke particles in their original configuration along with the other materials present. This is not a representation, but the actual physical presence of the particles, granules, fiber fragments, hair, dander, and other materials.

Tests answer questions. Analysis of smoke particles after the Station fire must answer the question of whether those particles constituted a loss. Testing is not required to identify the chemical composition of the particles because there is no difficulty establishing their source. They appeared suddenly when smoke from a forest fire inundated the community.

Establishing if a real loss occurred is contingent upon whether the quantity of the smoke particles was sufficient to diminish the appearance, utility, or life expectancy of the property. That is the only question. The answer is available from microscopic examination of samples representing conditions at the time of the loss.

In my role as damage investigator, I have analyzed hundreds of smoke samples over the years with reflected light microscopy. The results of these analyses have helped restoration contractors, property owners, and insurers determine whether significant smoke particles were present in electrical systems, electronic controls, paintings, statuary, and historic objects.

The corrosive effect of untreated smoke particles has been well established. Unfortunately, the misuse of legitimate test methods has enabled some insurers to deny the significance of potentially corrosive combustion particles and other aspects of smoke damage. When knowingly used to avoid payment of smoke damage claims, this practice is both reprehensible and dangerous.

Martin L. King, ASA, CR, is a technical advisor for the Restoration Industry Association in the area of fire damage restoration and is principle investigator for Martin Churchill Associates. He has testified as an expert witness in insurance-related litigation and frequently acts as arbitrator in insurance disputes. In addition, King is the author of the RIA Guidelines for Fire & Smoke Damage Repair and has published more than 300 articles in various trade journals.