California wildfires are prominent in the news. Many are rightfully concerned about the dangers posed from flames, heat and active smoke. However, soot and debris left in fire damaged buildings pose a significant and often overlooked danger.

I was in a condominium on Saturday which suffered significant fire damage. I was astonished that nobody had told the president and others of the health and safety dangers associated with fire debris and soot. I mentioned this issue earlier this year in, Insurance Company and Independent Adjusting Firms That Do Not Provide Personal Protection Equipment to Fire Claim Adjusters Are Violating OSHA Standards. I would strongly suggest that insurance company adjusters and their expert fire consultants warn their insurance customers of these dangers following a fire.

Industrial hygienist Dawn Bolstad-Johnson wrote an excellent article, The Hidden Hazards of Fire Soot, and noted:

The documented hazards of fire soot date back to 1775 when Percivall Pott, an English surgeon, discovered an association between exposure to soot and a high incidence of scrotal cancer in chimney sweeps. This was the first occupational link to cancer, which ultimately led to the science of epidemiology and the Chimney Sweeper’s Act of 1788.

Exposure to soot may not be an obvious health hazard to conservators who are exposed to soot during the treatment of fire-damaged materials. However, the term “fire soot” refers to smoke residue on surfaces, a complex mixture of substances that is often representative of what was in the fire smoke. Fire soot should not be treated simply as ‘dirt.’

Smoke is a complex mixture of different gases and particles, which results from the various materials that burn during a fire event. A typical structure fire (residential home or business) may involve the destruction of plastics, foams, fabrics, carpets, wood products, synthetic fabrics, wool, and asbestos-containing materials. Respiratory hazards connected with exposures when working in an environment that has been sullied by a fire event differ from those from the past, because the materials that our belongings are made from have changed over the years. For example, plastics and other synthetics are much more prevalent in our homes and studios today. It is important to recognize that these materials undergo pyrolysis during a fire and become the deposits that are identified as soot.


If you are asked to enter a fire damaged building to conduct an assessment, or. . .work on fire-damaged materials or other articles. . .Consultation with a health and safety professional is always recommended in these circumstances.

The presence of debris piles that may contain many other materials will probably present other chemical hazards. For example, formaldehyde, a known human carcinogen, is found in the glues that comprise plywood and oriented strand board (OSB), as well as many plastics, carpets, textiles, and other materials commonly found in typical structure fires. The geometry of the debris pile can often trap toxic chemicals like formaldehyde for days. The recommended personal protective equipment for working in a fire damaged building, includes the following:

Wear a full-face, air purifying cartridge respirator, equipped with CBRN canisters. These are the only canister cartridges that offer some protection from form- aldehyde. Formaldehyde is one of the most pervasive toxic chemicals and is found at nearly every fire due to the content load. Note that organic vapor cartridges will not work for formaldehyde.

Wear breathable disposable clothing.

Wear nitrile gloves.

Wear safety glasses.

Most people do not understand the danger of soot and smoke. They also do not understand how particulates can spread from one area of a building to areas far removed from the original area of fire. Smoke Damage: The Lingering Hazard after the Fire, warns of the following:

One of the sneakiest and most hazardous effects of a house fire, however, is smoke damage. When your property experiences any sort of fire damage, no matter how large or small the incident is, smoke will billow and spread throughout the entire structure. The smoke will want to travel to cooler areas of the home, traveling through any pipeline or wiring crevice, staining and smothering your structure with an unpleasant odor.

Even a very small appliance fire addressed quickly, can spread smoke to almost every room of the home. That’s why smoke and soot cleanup are hardly a DIY project, as many areas are not easy to restore – even for the handiest, most seasoned homeowner. Cleanup for smoke damage requires professional cleaning equipment and techniques to ensure that nothing is excluded. Trying to clean smoke and soot on your own, may result in more destruction and loss of valuables. In addition, [people] tend to overlook areas such as air ducts and vents.

When smoke gets into your ducts and vents, the tiny smoke particles tend to find their way into your HVAC system may linger there for months, undetected. Breathing these particles in is a health detriment and can lead to irritation in your lungs and possible scarring of the alveoli. (Emphasis added)

A professional fire restoration company, Rainbow International, noted on its website:

Leftover smoke and soot following a fire are more than just smelly and unsightly. Exposure during fire restoration efforts can adversely affect your health. Children, the elderly, and those with weakened immune systems are particularly at risk when exposed to smoke and soot. Its effects have been known since the 18th century, when the British Parliament passed the Chimney Sweepers Act in response to its association with cancer – the first ever occupational health legislation.


When combustion occurs during a fire, not all materials burn cleanly, resulting in smoke and soot. These waste products – solids, liquids, and gases – may be composed of various chemicals which are harmful to your health. Today’s modern structures hold an array of chemicals not found in early homes, including plastics, foams, fabrics, carpets, wood products, synthetic fabrics, wool, and asbestos-containing materials, which could result in health hazards that make fire restoration a dangerous and difficult task.


Exposure to smoke and soot during fire restoration may occur via the skin and eyes, inhalation, and ingestion. Because airborne soot particulate is invisible, you may unknowingly be affected. Once soot enters your blood stream, it can cause a wide array of serious health issues, including respiratory issues, shortness of breath, bronchitis, asthma, stroke, heart attack, cancer, and premature death. In infants, even short-term exposure to soot has been shown to have lifelong health consequences, permanently altering developing respiratory systems.

What kind of toxic of materials can be found in smoke and soot during fire restoration?

•Mesothelioma (cancer) causing asbestos fibers from building materials used in the 1950s-1980s.

•Carbon materials can produce carbon monoxide, hydrogen, ammonia, nitrogen oxides, and tar.

•PVC may create hydrogen chloride, phosgene, dioxin, chloromethane, bromomethane, and halocarbons.

•Sulfur can form hydrogen sulfide, sulfur dioxide, and thiols that can cause residual smoke odor.

•Partial oxidation of released hydrocarbons can yield formaldehyde, acrolein, furfural, ketones, alcohols, phenols, cresols, carboxylic acids, and more. . . .

•Even wood smoke released shares more than 100 chemicals also found in cigarette smoke.

Every fire loss should be treated as a hazardous area. Insurance adjusters should always make certain that qualified hygienists are part of the team that can certify a fire damaged building is repaired in such a manner that it is free from the dangerous byproducts caused by combustion of modern materials.

  • shirley heflin

    Dear Mr. Merlin:

    Informative post. I’m a FL Native and – while wildfires are not as prevalent here as they are in CA – we have our share of fires. When I read your post, I was reminded of all the precautions, safety gear, etc., that must be used in mold removal. The hidden toxins contained in mold debris, soot, fire debris, etc., pose tremendous health hazards to anyone breathing them – especially those breathing them day after day. All of them, no doubt, require expert removal intervention.

    Respectfully,
    SHIRLEY HEFLIN
    Tampa, FL