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Fire-related Particles Detection and Identification

Detection and Identification of Fire-related Particles – IESO/RIA Standard 6001 and Beyond

By Dr. Michael Berg, EMLab P&K Senior Molecular Biologist

In February 2012, a new standard to determine the presence of fire-related particles has been approved by the American National Standard Institute (ANSI). The document (IESO/RIA 6001-2011 Evaluation of Heating, Ventilation and Air Conditioning (HVAC) Interior Surfaces to Determine the Presence of Fire-Related Particulate as a Result of a Fire in a Structure, http://www.iaqa.org/standards) was produced by the Indoor Environmental Standards Organization (IESO) in close cooperation with a committee convened by the Restoration Industry Association (RIA).

The new standard sets guidelines to evaluate if fire-related residues have been deposited on HVAC interior surfaces. It does not address the identification of hazardous materials and/or the source material that has been burned. In this article, we will discuss the new standard and additional further analyses that EMLab P&K is able to offer to shed light on the potential sources and impact of fire related particle material.

Indicators of Fire-related Particles
Almost all fires produce char, ash or soots in varying amounts. Char consists of irregular shaped fragments of combusted material that are greater than one micron in size. A trained microscopist is able to identify char using a light microscope, and differing fuel sources will produce char particles with different morphologies. The IESO standard focuses on non-reflective, dark particles, and does not allow for differentiation between char or other particles that might emulate this condition, such as rust or darkened paint. Ash particles consist of fuel material that has had almost all of the organic material burned away, leaving inorganic remnants that are often crystalline. The IESO standard does not consider the presence or absence of ash. Soot particles are smaller particles (typically 10 - 50 nm) formed from incompletely combusted, volatile fuel material, and considered a secondary indicator of fire residue. Soot particles may darken the surface of a wipe sample and they can cluster to form agglomerates as large as 1 mm. A trained analyst using appropriate light microscopy is able to identify soot and differentiate it from dirt or char particles. If a primary indicator (char) is present, the standard does not require analysis of a secondary indicator (soot).

Sampling for fire-related particle material on HVAC interior surfaces can be performed in the same manner as surface sampling for mold. "Clear" or "Crystal Clear" 3/4-inch wide and 2-inch long transparent tape is pressed down on a relatively smooth area that is likely to have deposited char or soot particles. Do not use frosted tapes. Alternatively, a small piece of colorless fragrance free cellulosic or synthetic wipe can be used to sample an area of approximately 100 cm2.

Laboratory Analysis
The laboratory will use light microscopy techniques such as stereo, polarized light and dark field microscopy to detect the presence of fire-related particles. The method described in the standard is not designed to provide identification of individual char particles or to determine the source of the burnt material. However, the standard does encourage additional testing methodology to provide insight as to source and association of these particles.

Why Test for Fire-related Particles
Disputes over insurance coverage for fire damages often arise in the context of partial losses. Partial losses typically include not only visible fire damage but smoke and water damage as well. The damage can arise from a house fire in the neighborhood, or from wild-fires. The United States has been experiencing an escalating number of catastrophic-scale wild-fires in the past 20 years, in particular in the South and South-West. Testing can also be useful in catastrophic situations such as natural gas explosions and refinery fires such as have occurred recently in California. The IESO/RIA standard 6001 provides a procedure and measure to objectively determine if fire-related aerosols have impacted the HVAC system of a building. Similar methodology can also be used to examine other surfaces in a structure, including walls, painted surfaces and siding.

Hazardous Materials and Fire-source Identification
It is not the purpose of the IESO/RIA Standard 6001 to describe or provide methodology to determine if hazardous materials are deposited in the char and soot or to identify the fire source. Fortunately, EMLab P&K with our partner lab, MicroVision Laboratories, Inc., is able to provide services that can address those issues. After initial analysis by polarized light microscopy, the use of scanning electron microscopy (SEM) in combination with energy dispersive spectrometry allows the lab to provide information on the elemental composition of fire-related particles. Additionally, fine soots below the optical resolution limit of light microscopes can be imaged and documented. Sample types that may be submitted include composite Micro-Vac cassettes, wipe samples and tape lifts.

Vegetative Char by scanning electron microscopy (SEM)

Vegetative Char by scanning electron microscopy (SEM)
Source: MicroVision Labs, Inc. (Used with permission)

The use of SEM reveals a much more detailed picture of soot, ash, and char particles than light microscopy alone. In the example above, char from plant material can be clearly identified and confirm wood as the fire source material.

Ash particle by scanning electron microscopy (SEM)

Ash particle by scanning electron microscopy (SEM)
Source: MicroVision Labs, Inc. (Used with permission)

Ash particle Energy dispersive x-ray spectroscopy

Ash particle Energy dispersive x-ray spectroscopy
Source: MicroVision Labs, Inc. (Used with permission)

When energy dispersive spectrometry is added to the high-resolution SEM analysis, the elemental composition of the particles can be determined. This may be helpful to determine the fire-source as well as detect hazardous material in the particle material. This cutting-edge technology and methodology can also resolve less obvious and more complicated claims such as residues from oil, coal or biomass-fired power plants. Several industries can benefit from this service, including homeowners and inspectors, insurance adjusters, law and environmental management firms, the oil and gas industry, and many others.

EMLab P&K is proud to be able to provide comprehensive services in collaboration with our partner laboratory (MicroVision Laboratories, Inc.) that meet the new standard but also go well beyond the analysis that is covered in the IESO/RIA 6001. All EMLab P&K locations accept samples for these analyses. Please do not hesitate to contact your account manager or project manager to discuss the strengths of these, as well as many other cutting edge techniques for your project.

1. IESO/RIA Standard 6001: Evaluation of Heating, Ventilation and Air Conditioning (HVAC) Interior Surfaces to Determine the Presence of Fire-related Particulate as a Result of a Fire in a Structure. 2012 Edition. An American National Standard.

2. Zybach, Bob, Michael Dubrasich, Gregory Brenner and John Marker. 2009. U.S. Wildfire Cost-Plus-Loss Economics Project: The "One-Pager" Checklist. Wildland Fire Lessons Learned Center, Advances in Fire Practices.


This article was originally published on May 2012.