Evaluating a
STRUCTURE FIRE
An IH Guide to Smoke’s Impact
BY MICHELLE ROSALES
Following a fire, property owners, insurance companies, and neighboring residents are looking for answers. What is damaged? Is it safe to return to my home? Are any of my belongings salvageable?
These questions can be difficult to answer, especially in cases where the fire is minor or where physical damage isn’t observed. IHs, using our knowledge about recognition and evaluation of hazards, can help answer these questions. However, assessing a structure fire is challenging even for IHs because few reference documents are available, and few methods exist for sampling and laboratory analysis.
This article provides general guidance on assessing the impact of a structure fire on properties and contents. The term “impact” refers to physical damage and the presence of surface contamination—for example, fire- and smoke-related particulates, or polychlorinated biphenyls (PCBs)—at the property. My purpose is not to outline a comprehensive assessment strategy for all types of structure fires and situations, nor will I provide guidance on evaluating environmental health risks or structural integrity issues following a fire. Each property and evaluation is unique and should be assessed based on project considerations and information provided.
Most structure fire consultants are retained by homeowners and insurance companies, specifically to help settle a dispute over smoke impact or to evaluate areas of concern that are not visually distinguishable. Preparation for assessment of a structure fire starts well before the site visit and begins with the gathering of background information. BACKGROUND Every thorough investigation begins with gathering as much background information as possible prior to arriving on site. Start by focusing on the “five W’s”: who, what, when, where, and why.
Who is requesting the assessment? A homeowner is typically concerned about the structure and its contents. Tenants might only be interested in their personal belongings. Identifying the stakeholders is the first step in developing an adequate assessment strategy. It’s important to consider that a structure fire might impact more than just the structure it started in: smoke infiltration can significantly affect neighboring structures and properties. Assessment strategies and sample locations may change based on the fire origin. For example, potentially affected neighboring structures may have different smoke pathways than structures with an internal point of origin.
What was the ignition source? The composition of smoke depends on the nature of the burning fuel—that is, the source—and the conditions of combustion. Structure fires typically involve the burning of materials such as plastics, electronics, and plaster that might produce a wide variety of hazardous compounds. Knowing what started the fire and what burned in the process will help you determine the appropriate sample and laboratory methods. For example, the burning of electronics can produce PCBs and various metal fumes, which can become airborne and eventually settle onto surfaces. Polycyclic aromatic hydrocarbons (PAHs) can be released into the air during cooking activities and during the burning of organic materials. Knowing what burned allows for the use of specific indicators to determine areas of potential impact without visible evidence.
When did the fire occur? Knowing when the fire occurred and how much time has passed between the fire and the on-site assessment will also help you determine the most appropriate sampling strategy. Will the indicators you selected based on what burned be appropriate and still remain on surfaces by the time you are there to assess? Have they volatized?

Where did the fire occur? Is the location industrial or residential? Is the place occupied for long periods of time? Are the occupants a sensitive population such as students at a school or patients at a healthcare facility? This would be an important question to ask when evaluating environmental health risk to occupants.

What is our scope of work? It’s unwise to form conclusions and recommendations when the purpose of the assessment is unknown. Are you there to determine impact to the structure? To evaluate contents or merchandise? To determine the environmental health risk to occupants prior to re-occupancy? Or to evaluate health and safety risks to remediation contractors?

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Disadvantages of being unacclimatized:
  • Readily show signs of heat stress when exposed to hot environments.
  • Difficulty replacing all of the water lost in sweat.
  • Failure to replace the water lost will slow or prevent acclimatization.
Benefits of acclimatization:
  • Increased sweating efficiency (earlier onset of sweating, greater sweat production, and reduced electrolyte loss in sweat).
  • Stabilization of the circulation.
  • Work is performed with lower core temperature and heart rate.
  • Increased skin blood flow at a given core temperature.
Acclimatization plan:
  • Gradually increase exposure time in hot environmental conditions over a period of 7 to 14 days.
  • For new workers, the schedule should be no more than 20% of the usual duration of work in the hot environment on day 1 and a no more than 20% increase on each additional day.
  • For workers who have had previous experience with the job, the acclimatization regimen should be no more than 50% of the usual duration of work in the hot environment on day 1, 60% on day 2, 80% on day 3, and 100% on day 4.
  • The time required for non–physically fit individuals to develop acclimatization is about 50% greater than for the physically fit.
Level of acclimatization:
  • Relative to the initial level of physical fitness and the total heat stress experienced by the individual.
Maintaining acclimatization:
  • Can be maintained for a few days of non-heat exposure.
  • Absence from work in the heat for a week or more results in a significant loss in the beneficial adaptations leading to an increase likelihood of acute dehydration, illness, or fatigue.
  • Can be regained in 2 to 3 days upon return to a hot job.
  • Appears to be better maintained by those who are physically fit.
  • Seasonal shifts in temperatures may result in difficulties.
  • Working in hot, humid environments provides adaptive benefits that also apply in hot, desert environments, and vice versa.
  • Air conditioning will not affect acclimatization.
Acclimatization in Workers