Is that smoke smell real or a phantom odor?

During a structure fire, heat and pressurized smoke can permeate the air, infiltrating walls, ceiling cavities, attic spaces and anywhere air can travel. After the fire is extinguished, porous materials begin the process of off-gassing and releasing volatile organic compounds (VOCs). These odors can last for years if the affected materials are not properly cleaned, deodorized, encapsulated or replaced.

Oxidizing gasses such as hydroxyls or ozone, the use of HEPA vacuuming and air filtration and other cleaning methods can greatly reduce smoke odors and particulate matter. However, in some cases, the standard methods of deodorization may not work. Adjusters need to realize that on a molecular level, any structure affected by fire or smoke may not be able to be totally sanitized. Furthermore, there are certain types of combustion byproducts in the air we breathe as well as chemicals and gases that current deodorization processes may have little to no effect. Insured’s who have experienced a fire often misinterpret the smoke deodorization process as a guarantee of complete air sanitation, which in most cases is impossible to achieve.

When difficult smoke odors are encountered, deodorizers or “re-odorizers” are often used to mask or camouflage them. Over time, these counteractant fragrances dissipate, and under the right conditions, whatever smoke odors were treated or concealed can reactivate and reappear. Here is where real trouble can begin.

In situations where an insured reports the smell of smoke after the deodorization process is complete, the first reaction may be to try to downplay the possibility that any real odor exists since all the chemicals, deodorizers and oxidizing agents must have done their work, right? But then you have to ask yourself: “Could the culprit be a failure of the deodorization methods deployed, an over-sensitive sense of smell on the insured’s part, a desensitized sense of smell on the adjuster’s part, both, or something else?”

In this article, we will explore this issue and take a closer look into smoke odors and one of the most complex of the five human senses — the sense of smell.

How does the sense of smell work?

The scientific term for the sense of smell is called olfaction. Olfaction comes from specialized sensory cells, called olfactory sensory neurons or OSN’s, which are found in a small patch of tissue high inside the nose. These cells connect directly to the brain and each has one odor receptor. Microscopic molecules released by substances around us — whether it’s coffee brewing or the scent of a flower or perfume fragrances — stimulate these receptors. Once the neurons detect the molecules, they send messages to your brain, and it identifies the smell. There are more smells in the environment than there are receptors, and any given molecule may stimulate a combination of receptors, creating a unique representation in the brain.

When OSNs become damaged or inflamed, they can send a distorted signal to the brain. In other cases, the smell signal can become blocked. This blockage prevents the smell signal from reaching the nose or the brain.

The human sense of smell is more sensitive than most might believe. For example, the odorant ethyl mercaptan that is often added to natural gas or propane as a warning agent can be detected at concentrations ranging between 0.2 parts per billion (ppb) and 0.009 ppb. This is equivalent to approximately three drops of odorant within an Olympic-size swimming pool. Extremely low detection thresholds have been reported for the odorants d-limonene and ozone as well. The lowest human detection threshold known is for isoamyl mercaptan reported at 0.77 parts per trillion.

Tips for a successful smoke odor remediation

If you handle enough fire losses, sooner or later, you will run across an insured who swears they smell smoke after the restoration company finished the deodorization process. Keep in mind that every fire has its own chemical makeup or DNA — the fuels that burned, the types of chemicals that have reacted or interacted, the duration of the fire, the intensity of the heat, the odors and gases the fire generates all contribute to the uniqueness and toxicity of structure fire environments. In addition, numerous new chemicals are being introduced into household products and building materials each year, many of which have never been tested or studied to determine what types of potentially toxic byproducts and odors they create when burned.

Before the restoration process begins, adjusters should consider the following steps:

1. Wear proper personal protective equipment before entering any fire-damaged building. Keep in mind that you have no idea what chemicals or toxins may be present or that the fire may have created.
2. Document the damages with a Matterport. This will provide a clear image for all interested parties on the severity of damage and help support your recommendations on what can be restored and what should be replaced.
3. Manage the insured’s expectations. Inform them of what restoration processes may be used and have the contractor explain what their smoke deodorization guarantee includes or does not include.
4. Be mindful of the air temperature and humidity. Cold temperatures, especially in the winter months, can cause certain materials to retain smoke odor, which can later release when the temperature rises. In some cases, the use of electric heaters may be necessary to raise the indoor temperature, which can help open pores in materials and release odors.
5. Have an independent laboratory conduct air and surface sampling to determine what chemicals, heavy metals and other toxins may be present. When these types of tests are conducted, a remediation protocol should be included (providing that the testing lab understands the methods of proper smoke odor and particulate remediation). This is similar to what hygienists create for mold remediation or asbestos abatement projects.
6. If you don’t think certain materials can be restored or if the cost of restoration exceeds the materials or items’ value, then consider replacement.
7. Once the deodorization process is complete, have an independent testing laboratory conduct a clearance test prior to beginning repairs or installing new materials. If this test passes, then you have scientific proof that during the slice of time that the remediation work was done and tested, the affected areas passed and were deemed safe for use or occupancy. Without a clearance test, the proof of a successful deodorization may end up in a battle of the senses — the adjuster’s sense of smell versus the insureds.

Sean Scott is a licensed general contractor in California who has spent over 43 years in the construction and restoration industry. Throughout his career, Sean has worked with all the major insurance carriers that underwrite residential and commercial policies and has worked directly with claims adjusters, independent adjusters, third-party administrators, public adjusters and attorneys. He has written and co-written a number of books on disaster preparedness and insurance, including “The Red Guide to Recovery – Resource Handbook for Disaster Survivors.”

Briana C. Scott is the co-author and editor for Heritage Publishing & Communications. She has been instrumental in providing and interpreting information regarding the ecological effects of disasters. She also adds invaluable knowledge and understanding of scientific processes and her research has been instrumental in raising awareness of a wide range of post-disaster health and environmental hazards.

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