One of the biggest reasons that some fire investigators think that a cold scene is a safe scene (it is not!), and the biggest problem when we go out and teach about fire investigator health and safety, is that they cannot see the health hazards at a cold scene. When we arrive at a working fire, we see the smoke and the flames, and we feel the heat. These tell our brains that there is a hazard present and that we should stay away or protect ourselves. However, when we go to a cold scene (when the fire has been out for at least 72 hours and there is no visible smoke, etc.) where the roof is burned off and some exterior walls, for example, are gone so that air is freely moving throughout the structure, and the sky is blue, and the temperature is pleasant, there isn’t anything to tell our brain that there are still health hazards present. 

According to the work of Professor John M. Cimbala at Penn State University’s College of Engineering, the average human can see particles in the air down to about 70 microns in size. If the particles are light-scattering, in the air where a ray of light is coming through a window, then down to about 10 microns. Now remember, a micron is one-millionth of a meter or 39 millionths of an inch. That is REALLY small. For comparison, the average human hair is about 75 microns thick, and a grain of table salt is about 125 microns. What is my point? 

A 2010 UL study found that soot particles in the air during overhaul were mostly smaller than one micron. This was confirmed by the 2022 paper published by UL’s Fire Safety Research Institute, which showed that submicron particles of soot persisted five days after a fire was extinguished (Horn et al., 2021). No, the particulates didn’t magically disappear; this was just how long they monitored and measured each of the eighteen different post-fire scenes. 

It is hard for our brains to comprehend a health hazard when we cannot see it. Unfortunately, when you go into a post-fire scene, you immediately stir up these microscopic particles of soot in addition to what might already be in the air. And, because you’re not wearing a respirator, you are breathing in these very tiny soot particles. The smaller they are, the further they go into your lungs, and this can cause health problems, including cancer, later in your life. 

A recently published study by the University of Miami (Bakali et al., 2024) described the results of the analysis of silicone wristbands worn by sixteen public and private fire investigators in North Carolina at 46 different fires between January 2020 and September 2022. The average investigation duration was two hours and twenty-eight minutes, with the shortest being nine minutes and the longest being seven hours. On average, the investigations were performed 3.7 days after the fire was reported, with one being sixty-one days after. Half were on the same day as the fire. The wristbands were then analyzed for the presence of sixteen EPA priority poly(cyclic)aromatic hydrocarbons (PAHs). 

PAHs come in two varieties. Lower molecular weight (LMW) PAHs are more volatile than their counterparts and are in gas form, whereas the higher molecular weight (HMW) PAHs are bound to the soot particulates and are a solid. Many of the PAH levels were found to be above the OSHA permissible exposure limit. Of these sixteen, one (benzo[a]pyrene) is classified by the International Agency for Research on Cancer as carcinogenic to humans, and the others are classified as probably or possibly carcinogenic to humans. (Jameson, 2019) 

Additionally, this study found a positive correlation between the length of time an investigator spent in the scene and the wristband PAH levels. There was also a correlation between PAH levels and the time since the fire was extinguished, with higher levels found at younger scenes and lower readings at older scenes. Even the one sixty-one days after extinguishment had some very high levels. These results should not be a surprise to anyone! Investigating soon after the fires are extinguished puts the investigator into an atmosphere where off-gassing is still in progress, and there is a greater amount of particulates suspended in the air. 

This study was significant because it is the first to examine PAH exposure in fire investigators. Its results validate the need for fire investigators to wear adequate and appropriate PPE, including respiratory protection, during all phases of the investigation, regardless of how long the fire has been extinguished. 

So, we have looked at some of the health-related issues associated with cold fire scenes; now, let’s examine their safety aspects. We all know that fire suppression is an intense, get the wet stuff on the red stuff quickly type of activity. On the other hand, a fire investigation should be a slow, methodical process. One of the first things you should do when you arrive at a fire investigation scene is to conduct an exterior and then interior site safety assessment while wearing appropriate and adequate PPE, including respiratory protection. This assessment, by the way, is required in Section 4.1.3 of NFPA 1033. It is also addressed in NFPA 921 in Section 13.2.3 regarding hazard identification and all of the subsections in Section 13.3. 

As we learn more about the health and safety issues in the post-fire scene, it is essential to take this research into account and adapt our policies and practices accordingly. The fire investigation profession, public and private, often does not have the safety focus that it should have and needs to have. While only a few fire investigators have been killed on the job in safety-related incidents, the bigger problem is those who have died years later from occupational illnesses that were very likely contracted on the job. And we don’t know how many have been injured because those statistics are not captured specifically for the fire investigation profession. 

Unlike a fire or other emergency scene where time may be of the essence and safety must be balanced with completing other objectives, a post-fire investigation scene should not be rushed into but instead handled in an orderly and systematic process. This includes developing a work plan (incident action plan), conducting a site safety assessment, briefing all workers, which includes a safety component, having defined and explained roles and responsibilities, and continually monitoring the scene for safety hazards that could appear. This is the basic premise of the incident command system (ICS) from a safety perspective. Using the ICS as a foundation is relevant because conducting a post-fire investigation, especially one of a large or complex nature, involves many moving parts, which is no different from any other public safety incident. It provides a roadmap for all workers to understand the work to be done (Incident Action Planning Guide, 2015). 

In addition to the health hazards present at almost every cold fire scene, the safety hazards can be huge, too. Without conducting the site safety assessment before you do anything else, you don’t know what hazards are present at your scene and what mitigation efforts are necessary to deal with them. They can be different in each scene. This increases the risk of you or someone else being hurt. And you need to be wearing full PPE when you do this! 

Mike Rowe (Off The Wall: The Origin of Safety Third, 2022) from the Dirty Jobs TV show says, “I’d put the desire to be safe after ‘the need to make money’ and ‘the willingness to assume risk.’ In other words, ‘Safety Third.’” Mike coined the Safety Third term and concept almost twenty years ago. Businesses, including fire investigation companies, exist to make money, first and foremost, so safety is not first. What about the government agencies, you ask? They exist to provide a service, and in the public safety world, that certainly doesn’t always equate to safety first. How many times at a working fire scene have you done a risk versus reward calculation in your head before taking action? There is a safety component to that calculation whenever you determine how much risk you are willing to take. And, in that situation and many others, we are typically willing to assume some level of risk. 

The problem is that while we make this risk versus reward calculation many times a day based on various factors, accidents happen when we become complacent and don’t take the basic steps that we should take into consideration during the calculation process. And that brings us back to where we started. When you arrive at a post-fire scene, where there is no emergency in progress, and you can take as long as necessary to do your job, the failure to take basic safety precautions because you have done this hundreds of times before and nothing bad happened so you will do it (whatever IT may be) again and will expect the same outcome. This is complacency. 

I was told many years ago in a leadership class that you can do things right, or you can do the right thing. I have remembered it and shared it many times over the intervening years because the words are so true. In the fire investigation world, that means that you can do the investigation as expediently as possible, checking off the boxes of the basic steps, OR you can follow the best practice safety procedures, including a site safety assessment and wearing PPE every time while you conduct a thorough scene examination. It’s your choice. However, by doing the right thing, you can minimize your exposure to the many toxicants and safety hazards that can be present in the post-fire environment, which will more than likely increase your likelihood of having a long retirement. And that should be everyone’s goal. 

References

Bakali, U., Baum, J. L., Louzado-Feliciano, P.,   Killawala, C., Santiago, K. M., Pauley, J. L., . . . Daunert, S. (2024, May).   Characterization of fire investigators’ polyaromatic hydrocarbon exposures   using silicone wristbands. Ecotoxicology and Environmental Safety.   doi:10.1016/j.ecoenv.2024.116349

Horn, G. P., Madrzykowski, D., Neumann, D. L.,   Mayer, A. C., & Fent, K. W. (2021, December 16). Airborne contamination   during post-fire investigations: Hot, warm and cold scenes. Journal of   Occupational and Environmental Hygiene. doi:10.1080/15459624.2021.2002343

(2015). Incident Action Planning Guide.  Washington, DC: FEMA.

Jameson, C. W. (2019). Tumour Site Concordance   and Mechanisms of Carcinogenesis, Chapter 7, Polycyclic aromatic hydrocarbons   and associated occupational exposures. Lyon, France: International Agency   for Research on Cancer.

NFPA 1033 Standard for Professional Qualifications   for Fire Investigator. (2022).   Quincy, MA: National Fire Protection Association.

NFPA 921 Guide for Fire and Explosion   Investigations. (2024). Quincy, MA:   National Fire Protection Association.

Off The Wall: The Origin of Safety Third. (2022, 7 March). Retrieved from Mike Rowe:   https://mikerowe.com/2022/03/the-origin-of-safety-third/