Evaluation of Fire Scene Contamination by Using Positive-Pressure Ventilation Fans

• NCJ Number: 218773
• Author(s): Perry Michael Koussiafes
• Date Published: October 2002
• Length: 5 pages
• Sale Source: US Dept of Justice Federal Bureau of Investigation
• Publication Format: Document (Online)
• Publication Type: Report (Study/Research)
• Language: English
• Country: United States of America
• Note: From Forensic Science Communications, V 4, N 4, October 2002; downloaded June 5, 2007.

Annotation

This study examined whether a gasoline-powered positive-pressure ventilation system could contaminate a fire scene.

Abstract

The findings indicated that exhaust from a gasoline engine-powered positive-pressure ventilation fan was not sufficient to produce contamination at a fire scene. Specifically, the results revealed that towel samples from both trials 1 and 2 were negative for gasoline contamination. However, a trace amount of some of the early components of gasoline was found on the activated carbon strips analyzed from trial 2. It was noted, however, that the contamination that might occur from gasoline-powered engines was not significantly similar to what would be expected from gasoline recovered from an accelerated fire. Positive-pressure ventilation fans are designed to reduce smoke, gas, and heat in a burning structure and are generally considered from the perspective of the fire fighter, meaning the main factors under consideration are safety, fire contamination, exposure to hazardous materials, and search-and-rescue efforts. The research method involved, first, the preparation of samples of 100 percent cotton terry towels cut in 25-centimeter squares and activated carbon strips cut to 21 millimeters by 5 millimeters. Samples were then tacked to a wood strip. The positive-pressure ventilation fan was erected according to standard operating procedures, which resulted in the fan output blowing air into the doorway of the structure and the fan’s engine exhaust vented to the left. The positive-pressure fan was operated for 30 minutes and samples were collected from each sample location at three separate times: 0 minutes following fan shut-off, 1 hour following fan shut-off, and 2 hours following fan shut-off. In a second trial, the only difference was that 250 milliliters of gasoline was spilled on the side of the gas tank of the engine of the positive-pressure ventilation fan and on the ground. Towel samples and an exhaust sample were then collected and analyzed for contamination. Figures, references