We all know that postfire assessment and cleanup is a complicated issue. Although many assessments rely on known problems and a visual evaluation, testing can be an essential component in addressing “invisible” contamination concerns or determining if any residual contamination is above the “normal” or “typical background” levels. But what to test for and how to use the results are big questions without clear resolutions. CONSIDERATIONS FOR TESTING Concerns are typically centered on particulate residues, mainly char, ash, and soot, but chemical contamination of volatile (VOC) and semi-volatile (SVOC) compounds can be a large part of the picture. Metals can be a concern in post-wildfire assessments as well, although more typically in the outdoor environment. Table 1 outlines the usual concerns for testing.
Particulate and VOC contamination are critical in different areas. Testing or accounting for one does not necessarily address the other, but the two do share some traits.
Particles are a surface and dust contamination concern. A thorough cleaning of the surfaces and removal of dust may take care of the majority of particulate contamination. However, the biggest problem with particulate contamination is the possibility of recontamination, especially in an extensive wildfire situation in which the source material—the char, ash, and soot from the fire—remains in the outdoor environment, and air movement as well as foot traffic can bring the fire residues back into the building. Ash, particularly from wildfires, can also create a corrosive environment that can cause additional damage.
Fire creates an incredible mix of chemical compounds. These range from light gases to condensable materials and from common hydrocarbons to unique fire breakdown products.
Postfire Assessments of the Indoor Environment
The ABCs
of Wildfire Residue Contamination Testing
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