The principal goal for fire investigators is figuring out how and where a fire started and where foul play is suspected, specially trained arson detection dogs are amongst their ‘tools of the trade’. It is common knowledge that dogs have a keen sense of smell, but the actual degree of sensitivity is amazing.
Smell is a dog’s primary sense, and it is 10,000 to 100,000 times more acute than humans. That analogous to being able to see and recognise something 500 meters away, a dog could see and recognize the same object 5000 kilometres away. Or, if you could taste a teaspoon of sugar in your coffee, a dog could taste a teaspoon of sugar in over 3.5 million litres of water. Read more!
In terms of detecting the residue of volatile organic compounds (VOC) that may be present at a fire scene from common accelerants such as solvents, gasoline (petrol) or diesel fuel, they have a sensitivity of 0.001 part per million (ppm). That’s an incredible 1 part per billion (ppb)!
However, what if a ‘sniffer’ dog isn’t available or the remaining debris does not allow for safe conditions? What if suspected residue is in an area to which the dog doesn’t have access e.g. ceilings, small openings? Dogs can also tire and become desensitised.
PIDs for Fire & Arson Investigation
Another proven scientific tool used in forensic fire investigations is the photoionization detector (PID):-
- PIDs are quick, simple to use and accurate for the detection of fire accelerants
- PIDs are very sensitive to commonly found accelerants and will detect hundreds of gasses and vapours in low concentration
- PIDs are non-destructive and will not affect the air sample which can be captured at the same time as the measurement for further lab analysis
- PIDs reduce the quantity and cost of lab samples required to reach a conclusion as to the cause of the fire
- PIDs are portable and battery powered making them ideal fire and arson investigation instruments
PIDS for Fire & Arson Investigation
Effects of high humidity on PIDs
Solving the problem of humidity
Choosing the right instrument
Ease of calibration & maintenance