When we think of the damage left by a structural fire many of us might have a mental image of a home destroyed, with family heirlooms smoldering in the ashes. What about homes that only experience a limited fire and are not a total loss? Is it just as simple as removing some fire-damaged materials and wiping off some residual smoke damage? Unfortunately, it probably won’t be that straightforward.
A structural fire can generate a plethora of by-products depending on the materials and conditions of the fire. The most obvious by-product is particulate matter, the vast majority of this can be visualized as smoke. Smoke is a cocktail of solid and liquid particles, gases, and vapors. Depending on the fuel source of the fire, smoke particles can be commonly composed of soot, char, ash, and metal oxides. After a fire some of these particles will remain airborne while others settle onto surfaces. In general, exposure to particulate matter can cause health effects can range from eye and respiratory irritation to more serious health effects such as decreased lung function and irregular heartbeat[note]Council-certified Fire and Smoke Damage (CFSx) Certification Program Exam Study/Review Guide Rev. 4-2017. ACAC. Phoenix, AZ. 2016.[/note]. There is even new research going on regarding environmentally persistent free radicals which may be present in a home or building following a fire.
Particles are a health concern, but the risks are increased when those particles consist of heavy metals. Some materials can release heavy metals or other hazards like asbestos when they burn during a structural fire. Heavy metal exposure is a major risk during and after a fire. Building materials can yield things like lead oxide and hexavalent chromium. Many of these metals pose health effects like increased cancer risks, developmental issues, and organ damage. These metals can persist in the environment if special care is not taken when cleaning and restoring the space. They can also be transferred from an affected area of the building into unaffected areas or outside of the building by firefighters or restoration professionals if proper care is not taken to decontaminate people or equipment moving in and out of fire damaged areas[note]Fabian, T., Baxter, C.S., and Dalton, J.M. Firefighter Exposure to Smoke Particulates. Underwriters Laboratories Inc. 2010.[/note].
Similar to heavy metals, some materials can release organic pollutants when they burn. Contaminants like dioxins, polycyclic aromatic hydrocarbons (PAHs), and environmentally persistent free radicals are a few organic pollutants that can be released by a number of synthetic and organic sources in a building.
Dioxins (and closely related furans) are a broad class of organic chemicals that are released when building materials burn. The greatest amount of dioxins are produced with the combustion of polyvinyl chloride (PVC), which is found in plastic pipes and some flooring and wall covering products. They can also be produced in great quantities when furniture laced with brominated flame retardants burn[note]http://www.iaff.org/HS/SubstanceExposures/PDF/DioxinFactSheet.pdf[/note]. Since dioxins are a whole class of chemicals, the health effects can be varied. Health effects from dioxins include cancer, hormone disruption, immune system damage, developmental and reproductive complications, and more. Dioxin was was also a chemical used in Agent Orange, and was the main cause of health effects from the application in the Vietnam War. Dioxins are environmentally persistent meaning that they are resistant to normal environmental degradation processes.
Polycyclic aromatic hydrocarbons (PAHs) are organic compounds that are released from incomplete combustion of organic matter, and are also present in coal and tar deposits. The main health concern from PAHs are different forms of cancer. These cancer links have been observed by doctors since the 1700’s when cancer rates in chimney sweeps were significantly higher than the general population[note]Dipple, A. (1985). “Polycyclic Aromatic Hydrocarbon Carcinogenesis”. Polycyclic Hydrocarbons and Carcinogenesis. ACS Symposium Series. 283. American Chemical Society. pp. 1–17. [/note]. These are the same chemicals that make cigarette smoke so carcinogenic. PAHs are semi-volatile meaning they may either be found in the air or condensed on surfaces.
Beyond discarding the fire-damaged contents and building materials, you should also consider the environmental concerns that may be present in the air or on surfaces. Many times these pollutants can travel to other parts of the structure that were never on fire. In a future blog post, I’ll cover how we at Indoor Science test for fire-related by-products, and often find problems on the opposite corner of the home or building. We can test to determine the extent of the fire, or test to evaluate the work of a restoration contractor after the clean-up.