Fire Related Particles – Part 1

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.

Fire Related Particles – Part 2

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.

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.

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6 Common Indoor Allergy Triggers

If cold, wintry weather is keeping you indoors, remember: Year-round, that’s home to many of the peskiest allergy and asthma triggers, according to the Environmental Protection Agency. So if you have allergies or asthma, it’s a good idea to ensure that your home is as free of triggers as possible—or at least find ways to reduce your exposure. Your doctor can help you develop a plan, but here is some advice to get you started.

Dust Mites

Microscopic insects called dust mites are the most common allergy and asthma symptom trigger, according to the American Academy of Allergy, Asthma and Immunology. They feed on human skin flakes and tend to thrive when rooms are above 40 percent humidity and at temperatures above 70 degrees. And while they like bedding and soft furnishings the most, they can be found anywhere in the house. To ward off dust mites, allergists recommend purchasing allergen-proof encasings for pillows, mattresses, and box springs, and washing linens in 130-degree temperatures every seven to 10 days. When it comes to cleaning, have someone else handle the vacuuming, or wear a mask. And use a vacuum that contains a HEPA filter or double-layered bag. Since stuffed animals collect dust mites, too, you’ll need a simple way to keep your child’s favorites trouble free.


The dander shed by pets can cause symptoms in susceptible people. But for reasons not completely understood, some allergic people are OK around certain breeds. While there is no such thing as a hypoallergenic dog, some breeds, such as poodles and Portuguese water dogs, produce less dander. To test how you or your child fare around a particular breed, visit a friend or family member who has a pet to see how you feel, otherwise purchasing any animal while potentially having symptoms is like rolling the dice.


Indoor air quality tests, if done properly, can let anyone who suspects they may have mold know for certain.  Mold can grow from leaks or elevated levels in humidity which can affect the immune system.  Having your home regularly checked and properly maintained can eliminate the chance of growth.  But prolonged water damage and insufficient dehumidification can lead to potentially dangerous growth which can cause several types of illnesses.


Cockroaches, an issue mostly in cities and the southern United States, are believed to play a large role in asthma in inner-city populations, according to the Environmental Protection Agency. The allergens are found in the saliva and feces of cockroaches.  Having your residence treated on a monthly basis can eliminate this threat, while storing foods in containers, putting away your pet’s dishes, cleaning up after meals, taking garbage out promptly, and fixing leaky faucets or pipes because roaches need water to survive, also help to rid your home of these insects.


Many people don’t think of pollen as having an impact indoors. But if you’re outdoors during nice weather, you can bring it in on your clothes or shoes. Pets can bring pollen into the home too, leading some people to assume they’re allergic to their pets when in fact they’re actually allergic to ragweed or another type of pollen. To combat this problem, consider wiping pets down when they return from outdoors, keep windows closed in the home and run air conditioning during warmer weather, and change clothes and shoes immediately after returning from outdoors.


While not a traditional allergen, cigarette smoke is often an irritant for people with asthma and allergies. Secondhand smoke, which irritates the already inflamed bronchial passages in asthmatics, can cause asthma attacks and worsen the severity of the attacks, according to the Environmental Protection Agency. Moreover, studies have shown that exposure to tobacco smoke has incredible impact on increasing risk of asthma in kids. So allergists recommend that parents avoid smoking around children altogether, both at home and in the car. It’s thought that because kids are still developing, they’re more susceptible to the effects of smoke, and they may breathe more rapidly, causing them to take in more smoke than adults.

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Simple Explanation of a HEPA Vac

Encountering a good bit of people throughout the year, many of them do not understand the function and the difference between a regular vacuum and a true HEPA vacuum.  I wrote a blog on this a while back, but instead of getting into many of the technical differences, I’ll explain the core ones using a shop vac and a HEPA vac.  HEPA stands for High Efficiency Particulate Air.  A shop vac collects air into the unit which swirls around the cabin and exhausts out of muffler.  Locating the muffler is easy because of the amount of air discharging out of the top rear of the unit.  A true HEPA vac has all the air only passing through the filter and it does not have cabin leaks.  Not having cabin leaks means that the unit is air tight, and it eliminates the chance of cross contamination.  Secondly, the air passing through the filter ensures that the air is now clean.  And third, the differences between a shop vac HEPA filter and a real HEPA filter are endless, including the price.  A general big box store filter costs about thirty bucks, while a real HEPA filter runs just under two hundred.  The shop vac will cross contaminate the work area not only because it has cabin leaks, but also because the exhaust will blow an enormous amount of air in the work zone.  So, if the unit is not marked, HEPA, then the unit is most likely a regular vacuum which is being posed as a true HEPA system.

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