Forestal, Raymond, E. Use of Ultraviolet Light in Fire/Arson, Bomb and
Environmental Investigation. Firehouse. Vol. 19. No. 9 (September 1994).
Abstract: Ultraviolet (UV) light is the band of wavelengths between
visible light and x-rays that cannot be seen by the human eye. The use of
UV light is a reliable method of identifying the presence of accelerants.
When certain substances are activated by UV light, they absorb energy which
is manifested as fluorescence, or light. Substances that fluoresce under
UV light include gasoline, kerosene, fuel oils and other petroleum fractions
such as benzene. There are other substances that fluoresce as well, and
investigators must determine when the presence of an accelerant is actually
UV light has been used to identify pour patterns, the shape of an accelerant
container and pour trails leading back to containers. UV light will indicate
accelerant long after its odor is discernable. Masking an accelerant will
not prevent its UV detection. Accelerant on skin or clothing will fluoresce
Areas illuminated by UV light can be photographed with slow shutter speeds,
long exposure times, a tripod, and special film or filters. An I lux camera
is an excellent tool for obtaining these images.
When using UV light, dual wave, portable, hand-held lights seem most
effective. The area should be as dark as possible. Protective eyewear should
be worn and you should not look at any UV light source without protection.
Reflective surfaces exposed to UV light can cause sunburn to eyes and skin.
And UV light is not to be used in explosive atmospheres. UV light does,
however, assist in the location of explosive residues.
UV light can assist in environmental investigations by indicating the
presence of hydrocarbons on land and in water. Illegal dumping has been
traced using this technique. Trace dyes can be used along with UV light,
and some radioactive substances fluoresce as well.
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