The Limitations and Advantages of Ultraviolet Light Sources in the Detection of Ignitable Liquids at

Fire Scenes

Sarah Kunkel

2006 MAAFS Annual Meeting

May 5, 2006

UV in Arson Investigation

• Ultra violet lights marketed to arson investigators for decades

• Very few reliable studies to support their claims

Ultraviolet Light Test Objectives

• Determine capabilities of UV light source

• Determine limitations of UV light source

• Determine whether UV light source is a practical approach to ignitable liquids detection at fire scenes

Ultraviolet Light Source

• Model UVSL-26P by UVP in California

• Rechargeable• Three modes of

operation– Short wave (254nm)

– Long Wave (365nm)

– Dual

Testing Performed

I. Amount of Ignitable Liquid

II. Time Exposure

III. Visualization of Various Ignitable Liquids

IV. Visualization on Various Materials

V. Visualization on Various Burnt Materials

I. Amount of Ignitable Liquid

• All amounts of gasoline tested on carpet and asphalt tile– 10 μL– 25 μL– 50 μL– 100 μL– 150 μL– 300 μL

I. Amount of Ignitable Liquid• All amounts detectable on carpet and

asphalt tile

50 μL gasoline on asphalt tile

50 μL gasoline on carpet

I. Amount of Ignitable Liquid

10 μL gasoline on asphalt tile

300 μL gasoline on asphalt tile

10 μL gasoline on

carpet

300 μL gasoline on

carpet

I. Amount of Ignitable Liquid

Close-up:

10 μL gasoline

on carpet

II. Time Exposure

• All tested on carpet and asphalt tile

– 30 minutes

– 60 minutes

– 120 minutes

– 180 minutes

– 240 minutes

– 300 minutes

II. Time Exposure• All amounts detectable on the tile and

carpet at 10 months

1st Day

10 months

later

III. Ignitable Liquids Tested• All liquids tested at 10 μL and 50 μL on

asphalt tile• Ignitable liquids tested:

– Gasoline (Unevaporated, 50%, 75%, and 90% evaporated, and Base)

– Diesel fuel– Lighter fluid– Linseed oil– Various ignitable liquids used to calibrate the

canine detection team

III. Ignitable Liquids Tested

• Only gasoline, diesel fuel, and linseed oil detectable on all material at all amounts

• Weathered gasoline fluoresces brighter than non-weathered

– 90%>75%>50%>non-weathered

• Base gasoline not detectable

• Gasoline from various companies indistinguishable

III. Ignitable Liquids Tested

90% 75% 50%

Weathered Gasoline

IV. Flooring Materials Tested

• Carpet

• Linoleum

• Foam Carpet Padding

• Fiber Filled Carpet Padding

• Asphalt Tile

• Wood Flooring

IV. Other Materials Tested

• 100% White Cotton T-shirt• Jeans• Human Skin• Manila Folder• White Printer Paper• White Notebook Paper• Yellow Notebook Paper• Paper Towel

IV. Flooring Materials Tested• Must use only short wavelength on

linoleum

• Carpet and asphalt tile worked under long, short, and dual wavelength

• Mostly questionable positives for fiber filled carpet padding and wood flooring

IV. Other Materials Tested

• Negative results on jeans and cotton t-shirt

• Skin– Remain detectable on skin between 8-9 hours– Canine team did not detect after 3 hours – Fluoresced after 5 hand washings

• Paper products– Both liquids fluoresced on all paper products– Light absorbed when liquid was still wet

V. Burnt Materials Tested

• Carpet

• Linoleum

• Foam Carpet Padding

• Fiber Filled Carpet Padding

• Asphalt Tile

• Wood Flooring

V. Burned Materials Tested

V. Burnt Materials Tested

• Only short and dual wavelengths visualized the ignitable liquids

• Gasoline less visible than diesel fuel on all materials

• Results varied from unburned materials– Less positive results – Carpet absorbed light

Additional Results

• Dawn detergent masks ignitable liquids from the canine teams but no affect on fluorescence

• Exposure to water does not affect fluorescence

Conclusions

• UV light only useful in detection of gasoline and diesel fuel

• Not affected by water, but burning of material does affect visibility

• Useful with small volumes and at long exposure times

• Fluorescence caused by dyes in ignitable liquids

Acknowledgements

• Don Brucker, Allegheny County Fire Marshal’s Office

• Bob Huston, Allegheny County Crime Laboratory

• Dr. Graham Rankin, Marshall University

References• DeHaan, J. D. Kirk’s Fire Investigation 4th edition. Prentice Hall,

1997. 405-11.• Forestal, R. Use of Ultraviolet Light in Fire/Arson, Bomb, and

Environmental Investigation. Firehouse Magazine September 1994: 48-50

• Brucker, D. Chief Deputy Fire Marshal, Allegheny County Emergency Services. July 18-27, 2005. Pittsburgh, Pennsylvania.

• U.S. Fire Administration. Arson in the United States (Topical Fire Research Series). The Administration. January 2001. 1(8): 1-3

• Ultra-Violet Products. Use of Ultraviolet Light in Arson Detection [Application Bulletin-UVP-AB-107]. 1997

• Stauffer, Eric. Technical Working Group for Fire and Explosives Discussion. March 21, 2006.

Questions???