Technical FAQ: methods, standards, and interpretation

Particle testing analyzes collected surface or dust samples (tape lift, wipe, micro-vacuum, bulk) for soot, char, ash, and black carbon — the deposited-residue question. VOC testing analyzes air samples (EPA TO-15A canisters, TO-17 sorbent tubes) for smoke-related volatile compounds — the gas-phase and odor-chemistry question. Complete investigations often need both.

TO-15A collects whole air in an evacuated canister and suits broad VOC screening by GC-MS. TO-17 pulls a measured air volume through a sorbent tube and suits targeted, time-weighted sampling with lower detection limits for selected compounds — provided the sorbent is matched to the compounds of interest.

Buildings normally contain particles and VOCs from cooking, candles, fireplaces, traffic, and consumer products. Comparison samples — outdoor air, unaffected rooms, neighboring units, pre/post remediation — turn 'compounds exist' into 'the pattern is meaningful versus expected background.' Their absence is the most common attack on a weak report.

The documented path of each sample from collection to laboratory receipt: sample ID, location, date and time, collector, method, packaging, transfer records. Without it, opposing parties can question whether samples came from the stated locations or were mishandled.

No. Non-detect means the target compound was not reported above the laboratory's reporting limit under that method and condition. It does not rule out compounds not on the panel, surface residues, HVAC contamination, or odor reservoirs in porous materials.

ANSI/IICRC S700-2025 is the standard for professional fire and smoke damage restoration, describing assessment of the presence, intensity, and boundaries of fire residues and odors. IICRC S760 addresses wildfire-specific restoration. ASHRAE Guideline 44-2024 covers protecting building occupants from wildfire smoke.

Qualified environmental consultants or industrial hygienists — AIHA recommends scientific training, CIH credentials where appropriate, and fire/smoke experience. The laboratory reports data; the professional connects it to the building, the event, and the limitations.

No. OSHA describes photoionization detectors as nonspecific — useful for locating sources and concentration gradients in the field, not for identifying compounds. PID readings guide where to collect laboratory samples; they are not evidence by themselves.

ASTM D6602 addresses distinguishing manufactured carbon black from other environmental particulate, including combustion soot. Fire investigation laboratories apply D6602-based microscopy to classify dark particles — because dark dust is not automatically fire soot; it can be rubber, carbon black, or ordinary urban particulate.

Re-sampling the previously affected areas after cleaning, ideally against pre-remediation baselines, to verify the targeted residues were reduced or removed. Clearance rests on the written scope, the cleaning methods used, HVAC actions, visual and odor assessment, and comparison samples.