As an organization that conducts field investigations, provides laboratory analysis of mold and particulate samples, and offers training classes related to various aspects of indoor air quality, Wonder Makers has extensive experience addressing questions related a whole range of indoor contaminants. One indoor pollutant that is often underestimated in regards to its impact on aesthetics and health is fire residue, such as soot and smoke. So, it was no surprise when a recent client requested our opinion about the best method for determining the effectiveness of cleaning efforts related to a fire loss. In this particular instance, the contractor was having difficulty in measuring how clean is clean enough after completing standard fire loss restoration efforts.
How Clean Is Clean?
Normally, when someone in the restoration industry starts asking how clean things really need to be, the first impulse of many contractors is to fall back on testing of some form. Surprisingly, in the fire damage portion of the restoration industry many contractors do not know the specific types of testing that are available for fire residue. Without sampling, the default position is to get things visibly clean (even to the point of meeting a white glove criteria), undertake some form of deodorization, and document the results with photos.
Where the circumstances or client demand verification of the quality of the work, there are many methods for verifying the professionalism of the cleaning. With training as a Fire Loss Specialist through the Restoration Industry Association (RIA), and contacts in the cleaning and restoration professionals built up during decades of work, the Wonder Makers team knows who to call. For the inquiry about cleanliness after a fire, we were able to connect the contractor with a laboratory that has a well-regarded reputation for knowing the details about proper sampling and analysis for soot, char, and ash. Since a relatively small percentage of fire jobs actually involve sampling, this was a new approach for the contractor to add to the “tool kit” for this particular project, and future fire loss situations as well.
A Simple Sampling System
So, as a savvy restoration contractor in your own right, you may be asking, how do I add this scientific evaluation criteria for the next time I need to have an empirical standard to test to on a fire loss? In other words, how can a contractor be prepared for a demanding adjuster or detail-oriented homeowner? The good news is, while many tests are possible to identify combustion byproducts, there is a very simple one which uses supplies that many restoration contractors already carry with them. Effective samples for fire damage can be collected with the single use Bio-Tape-style slides that are commonly used in the industry to clarify whether the black fuzzies in the corner are mold or dust. That same Bio-Tape sampler is also great tool to determine whether that black smear is grease or soot.
Always check with your lab of choice before sending in soot samples, but the reading process is similar to many other microscopic contaminants. Instead of the stained spores that are identified on a bio-aerosol sample, the analysist identifies the remnant structures left behind by the various types combustion byproducts. What is different from the mold analysis is that evaluation of soot and ash is often done with black light in combination with a more typical optical and phase contrast microscopy.
While many compounds can be identified this way, not everything is perfectly clear at the level of magnification that can be achieved by simple lenses. Occasionally, depending on the type of fire, the heat generated during the combustion process, and the fuels that were consumed, a more powerful microscope is needed. In those cases, the most common choice is to turn to a scanning electron microscope or transmission electron microscope. However, it is worth noting that not only are these more intense microscopes more expensive to operate, leading to higher per sample costs, the process of preparing slides for analysis can often destroy the more physically fragile types of combustion residue. So, unless there is a compelling reason to opt for the more specific analysis, such as attempting to identify the presence or absence of a specific chemical, then direct visual analysis is typically the best for determining project cleanliness.
Sample Results Must Be Understood
Regardless of what the sample collection method is used or which microscopic analysis equipment is employed, it is important to remember that those two factors must be supplemented if the question of cleanliness after fire restoration is answered. The critical question that needs to be understood upfront is what data interpretation criteria is going to be utilized when reviewing the sample results to determine if the work area is clean?
Even this selection of sample data interpretation criteria may need to be broken down into two categories. While the sampling process may be the same, evaluating results may be different for the contents that are being cleaned and salvaged from a fire loss as compared to the structure. One critical difference is that compared to contents, sampling of the structure is most effective mid process. Cleanliness sampling needs to occur once the cleaning and replacement of damaged structural materials has been completed but before the rebuild has begun.
It should not be surprising that the recommended criteria for evaluating a built environment, such as the framing left behind in the burn area after the completion of the initial fire clean, is different than the criteria that is often applied to contents. Tape samples from framing members and other surfaces attached to the structure are allowed to have a very low amount of fire residue present; although the criteria is not zero.
A Different Criteria For Contents
Even though a low-level of combustion byproducts are present in our environment from outdoor exposures and interior cooking, the criteria for evaluating tape sample results should be aggressive. Typically, a result from a tape sample taken from cleaned structural materials should be equal to, or less than, one percent (i.e., ≤1%) combustion products. Extensive experience from Wonder Makers, and a number of other labs and consultants, has shown that documenting this level of cleaning effectiveness will be sufficient for all but the most chemically sensitive of occupants. Even with this aggressive criterion, remember that the Bio-Tape sample is collecting material from the surface of less than one square inch (3/4” X 1”). Therefore, the sample collection locations should be representative of worst-case surfaces after the entire work area has undergone a thorough visual evaluation.
Having discussed a standard for the built environment, the next question becomes, what is the standard for contents? Unlike the structure itself, the contents are typically cleaned off-site in a location otherwise free from combustion indicators. This reality means that there is a default potential for a higher degree of cleanliness.
Another consideration is the greater variety and efficacy of cleaning techniques that can be employed on a more manipulatable object than the framing of a house. To our knowledge, no one has an ultrasonic tank big enough to dunk a house in, and if they did, getting the house to the tank or vice versa would probably not be cost effective.
However, many content cleaning facilities have access to ultrasonic wash tanks, multistage cleaning sinks, Esporta systems, steam cleaning sets for upholstery, and all the other content cleaning paraphernalia that has been developed in the pursuit of excellent work. Therefore, a clean standard for tape samples from contents is that each tested item should show no combustion byproducts. While this standard may seem harsh at first, the reality of the situation is that the capacity for cleaning contents is higher. Additionally, the occupants will be more directly interacting with the contents than they will be with the structural building materials that will be sealed and covered over as part of the rebuild process.
When Are Samples Of A Fire Loss Necessary?
With the understanding of what sampling might look like, as well as a clear end point for the sampling, a discussion of the proper time for sample collection also needs to be considered. There are three basic categories of when sampling can make sense; presented below in order of the usefulness of the sampling.
First, sampling can be useful in fire loss cases that are getting hung up in the search for a mystery odor. Unfortunately, there are frequent occasions where the parties involved in a fire loss cannot agree on what an appropriate level of clean is for structural members where the discoloration may be from something other than smoke and soot deposition. In these cases, the scientific evidence from sampling can be instrumental in resolving the dispute.
Second, every restoration contractor has occasionally encountered a project that just has the smell of the litigious about it. There are times that it is clear that a project is headed towards a court case, sometimes because the customer outright states that they are planning to sue. Other times, with the history that the restoration contractor has from their years of service they can just feel the lawyers coming. On those projects having the analytical data to back up the photographic evidence can save a lot of time and trouble in avoiding a long, drawn out, lawsuit.
Third, there will always be projects where a higher degree of certainty is required after the fire cleaning and before the rebuild. With an agreed upon clean standard, and an outside lab for the testing, clean can be confirmed before the new drywall hides any potential issues.
Tape Samples For Fire Restoration Are A Valuable Tool
Despite the fact that tape samples of fire residue do not seem to be very well known in the restoration industry, they can be incredibly useful. Having documentation of the level of soot and ash, both before the cleaning process has begun and after, provides a level of documentation that confirms the effectiveness of the cleaning. In addition to guiding the contractor’s efforts, such samples give the adjuster and the owner clarity in regards to the professionalism of the remediation. With the ease of sample collection, and at a relatively low cost per sample for the analysis, there is no reason why such samples should not be collected more often.