Wildfire Investigations

• Date and name of wildfire occurrence
• Location and proximity of wildfire relative to the property
• Prevalent wind direction(s)
• Ambient air quality monitoring station data if available
• Cleaning or restoration performed to date
• Building and site characterization
• List of other potential fire residue sources (e.g. smoking, fireplace, or candle use)

The visual inspection of the subject property is the most important part of the investigation. Note: Surface particles found at properties located farther away from the wildfire or investigated after a significant period of time may be difficult to assign to wildfire impact since they may be confused with other particles typically found in household dust. For fire-related insurance claims, the following potential residue depositions should be investigated:

• Selective deposition and/or accumulation of combustion-related particles. The products of combustion are not all black because when the carbon is consumed, the result is generally white, yellow, or red ash.
• Ghosting appears as a visible pattern on a surface outlining the borders of an object. Note that ghosting may also result from burning candles, lack of ventilation of wood-burning fireplaces, cigarette smoking, and cooking exhaust.
• Threshold streaks can be visibly seen as dark streaks, splotches, or dark lines, commonly observed below doors.
• Smoke webs start as individual microscopic combustion particles which become linked together to form strands or chains, become visible, and look like spider webs.
• Corrosion may occur if gases and/or particles begin to oxidize or rust metal items.

Sampling Techniques

Sampling and sample analyses are key to assessing environmental quality, potential wildfire residue impact, and identifying possible causes of health complaints. The sampling protocol is designed to confirm or discount the presence of combustion-generated particulate matter accumulation. Particles of the most interest are the products of incomplete combustion of plant matter resulting from a wildfire (such as timber burned structures) and are defined as:

• Char: composed of particles larger than one micrometer produced by incomplete combustion.
• Ash: typically defined as a mineral residue generated after the combustion of char.
• Soot: a submicron black powder generally produced as a by-product of combustion or pyrolysis.

Although most sampling is directed at collecting particles associated with the wildfire, sampling for volatile organic compounds (VOCs) and semi-volatiles (SVOCs) is also important to complement particle analysis and provide essential information to assess potential health effects. Some SVOCs, such as polycyclic aromatic hydrocarbons (PAHs), penetrate certain porous surface materials, such as fabrics, and can be detected even months after initial exposure. Sampling techniques used include:

• Tape lift samples
• Wipe samples
• Micro vacuuming
• Ambient air sampling for dust
• Ambient air sampling for Total Volatile Organic Compounds (TVOC)