Image: The Sand Fire near Santa Clarita, California, U.S. in July 2016. Credited to Getty Images and Attila Adam.

AIHA’s chief science officer, Michele Twilley, DrPH, CIH, recently spoke with Dawn Bolstad-Johnson, MPH, CIH, CSP, FAIHA, about the assessment of structures that have been damaged by fire. Their conversation covered instrumentation, sampling and analysis, issues for homeowners, forthcoming guidance from AIHA’s Real-Time Detection Systems Committee, and other aspects of post-fire assessments. Bolstad-Johnson is CEO and founder of Kaizen Safety Solutions in Phoenix, Arizona.

This is the first of two posts that present transcripts of Twilley’s conversation with Bolstad-Johnson. It has been edited for length and clarity.

Michele Twilley: What should an IH professional know prior to engaging in a wildland fire assessment?

Dawn Bolstad-Johnson: It is imperative that the industrial hygienist understands what was on fire and the composition of the fire emissions (soot, char, ash, acid gases, heavy metals, aldehydes, hydrogen cyanide, sulfur dioxide, nitrogen dioxide, VOCs, hydrocarbons, etc.). What I'm seeing in my practice through legal work and reviewing numerous IH/CIH reports is that most are approaching these cases as if they are forest fires, and there is a lack of reference or review to current published literature on the urban wildfires and their fire emissions. Consultants simply get the call, and they go out and sample for soot, char, ash, and maybe use a photoionization detector (PID) to sample for volatile organic compounds (VOCs), and that's about the extent of the investigation.

Google scholar is a great place to start. The National Academies publication “The Chemistry of Fires at the Wildland-Urban Interface” gives lists of emissions that are consistent with a house fire or a car fire. Fire emissions are directly related to what was on fire. They are all different, and understanding the fire emissions is going to determine your entire sampling plan.

A few years ago, there was an article in The Synergist, “The ABCs of Wildfire Residue Contamination Testing,” that was written, in my opinion, mainly for biomass fires, which are forest fires. There are chemicals generated in biomass fires that can be somewhat unique.

Fires that involve structures are much different and have much more complex mixtures of fire emissions. In the ABC’s article, there's sampling methodology recommended to understand whether a property has been impacted by fire, and I believe this methodology was developed by a lab, not a regulatory agency. The lab determined primary and secondary indicators, and I believe that probably was designed to protect insurance companies from fraud and also help homeowners determine if their home was impacted from wildfire smoke and biomass, not necessarily fire emissions from structures, synthetic contents and vehicles. The sampling methodology for all post-fire evaluations needs to be based on what actually burned. I've reviewed IH reports that have used this sampling methodology after a car fire in a garage. The results are negative. The lab results for a biomass test used in a metal and synthetic fire are falsely interpreted to indicate there's no problem after two cars burned in a homeowner’s garage. The problem is it is the wrong test.

But what CIHs don't fully realize is the differences in fire emissions generated from a car fire compared to a biomass fire. I think there's a big gap in understanding how fire smoke moves, and that the HVAC system is the major highway that delivers fire debris and fire emissions to all the rooms in the house. If smoke gets in the HVAC, whether the system was on or off, that's like an Autobahn for particles to sail through to all the rooms. Smoke is going to look for a place to cool off. In homes that have a lot of smoke, you may see thermophoresis where particles have collected in certain areas as a result of temperature differentials.

As CIHs and leaders in the field, we should be taking the time to review current literature and do our homework before we go out and sample post-fire environments. Bringing a PID to check for VOCs and a package of tape lifts may not be the right tools. The problem with the PID is it doesn't see most of the common fire emissions. The ionization potential for most chemicals in fire emissions is higher than the 10.6 eV lamp that's commonly used in PIDs. That means that the PID will read “zero” on the display even when formaldehyde could be higher than ceiling concentrations.

If it was a house that burned, then look up what the fire emissions are in “The Chemistry of Fires at the Wildland-Urban Interface” and see if a PID will even detect all of the common fire emissions. If it doesn't, then that's the wrong tool. Maybe you need to go to traditional industrial hygiene sampling pumps or use a silicone wristband to see what's in there.

If an IH is using a direct-read instrument, it is imperative that the user understands the instrument to a level of proficiency. It is more than just, “Read what's on the screen.”

When I sample, I use many layers of confirmation. The particulate data can stand by itself. The VOC data can stand by itself, and the soot, char, and ash data can stand by itself, and the chloride anion sampling can stand by itself. But when you put all the layers together, do they all say that there's a problem here? Typically, they will. The hygienist has to look at all the data in totality when making an assessment on health and safety or level of fire damage, and then you have to work with other trades to help remove fire damage. For example, if high levels of char or ash are found inside the breaker box, a licensed electrician should be consulted for further evaluation.

If you're swabbing the breaker box and can see fire debris, char, and ash, it may be a good idea to also collect a sample for chloride anions. Any plastics—PVC, for example—will have some form of chlorine in them. What a lot of hygienists don't realize is that concentrations of chloride anions will etch the electronic board. It may not fail tomorrow, but over time it's going to start arcing, and then the whole board's going to be fried, and one day your microwave doesn't work.

I've done passive badges for formaldehyde in a home a year after the fire and still found formaldehyde in the environment. The house was vacant and had been stripped down. All the carpeting, floor coverings, and furniture had been removed, and we're still seeing off-gassing. When you're dealing with a chemical mixture as complex as fire smoke, the chemical decay can also produce new combinations of chemistry.

The other consideration that is often disregarded is the fact that soft goods and building materials have the ability and capacity to absorb many fire emissions. The porous building materials and contents become a reservoir that holds on to the fire emissions for years.

Another factor to consider is proximity to the fire. Spatial and temporal references are defined in “The Chemistry of Fires at the Wildland-Urban Interface.” The proximity could be several kilometers. Fire often creates its own weather. During some wildfire events, the smoke will swirl around, and when the wind changes, some of the homes that may have had smoke intrusion on day 3 will get smoke intrusion again on day 14. Part of the post-fire evaluation must include a review of the weather at the time of the fire. Review before and after photos of the neighborhood on Google Earth to help understand how much exposure a home endured.

Fire emissions create a very complex, dynamic mixture of toxins that were generated from whatever was on fire. Again, fire emissions from a vehicle fire are much different than emissions from a forest fire.

I would direct consultants to do their homework. Read the literature at the very least. Read “The Chemistry of Fires at the Wildland-Urban Interface.” Then you will have a better understanding of the fire emissions and can set up your sampling plan to match what was on fire to do an effective job as an industrial hygienist. We're there to anticipate, recognize, evaluate, control, and confirm the hazards that impact human health.

Speaking of “confirm,” what level of clearance sampling should be done after the remediation is complete? Nobody has defined that. I believe clearance sampling should be a subset of the initial evaluation. And again, it's going to depend on what was on fire. How close was the home that you're sampling to the fire? Was it next door? Was it three blocks away, or was it five miles away?

When I do these evaluations, I'm in full-face respiration with CBRN (chemical, biological, radiological, nuclear) canisters because I don't know what's in there until I'm done sampling. I know it's not oxygen deficient, but I don't know what chemicals I may be exposed to, so I think full-face respirators with CBRN canisters are the best protection for doing these evaluations. The material the respirator is made of is also important. The painters' full-face respirators are usually made of silicone, which can absorb the chemistry in post-fire environments. Respirators made out of butyl rubber are best.

If all you have is a PID, that's not giving you the full story. You may want to consider using a more advanced tool like a gas meter or Fourier transform infrared (FTIR) spectroscopy or going back to traditional industrial hygiene sampling pumps where you can put them in multiple areas and look for contaminants on badges. Evacuated Summa canisters have their place, but they can be very limiting because they sample only one location. What the direct reading instruments bring to the table is that you can sample four corners in the center of every room in the house instead of doing just one Summa canister in the garage or kitchen.

Talk to the homeowner, get their story, look at the data, look at the lab data, look at your real-time data, look at your visual observations, and put that whole puzzle together. I think that’s the best approach for not only assessing the fire damage but also potential exposures that the homeowners may have. A lot of times, the homeowners get fed up because they can't get the house clean. They can't stay in the house without having health effects, so they'll just sell the house and put a disclaimer that they did everything that the insurance company directed them to do. To me, that's a public health problem, because now we just passed the problem on to an unsuspecting family that may have young kids.

For the past month, I have been sampling in Pacific Palisades and Altadena. Homeowners are concerned about lithium deposits in their homes due to the high number of electronic cars that were burned in these fires. The homeowners want to know if it is safe to live in their homes after the fires. Homeowners have described the odors in their homes as rancid smoke, burned plastics, sweet burning smell, etc. What better profession than the field of industrial hygiene to help compete these dynamic hazard assessments?