Certified Fire Investigator Practice Exam

What can be concluded about organic materials and their relation to self-heating?

1. They never lead to ignition

2. Oxidation from bacteria can lead to self-heating

3. They cool quickly when exposed to air

4. They require external heat sources to ignite

The correct answer is: Oxidation from bacteria can lead to self-heating

The conclusion that oxidation from bacteria can lead to self-heating is based on the understanding of how organic materials decompose. Organic materials such as plant matter, food waste, and other biological substances undergo microbiological decomposition, which involves the action of bacteria. During this process, bacteria generate heat as a byproduct of their metabolic activities—this heat can potentially raise the temperature of the organic material enough to induce self-heating. Self-heating occurs when the heat generated internally through microbial or chemical processes exceeds the heat lost to the environment, leading to a rise in temperature that can, under certain conditions, result in ignition. This phenomenon is often observed in compost piles, where organic materials are broken down by bacteria, resulting in significant temperature increases. In contrast, the other options do not accurately describe the relationship between organic materials and self-heating. Organic materials can indeed lead to ignition under suitable circumstances, they do not cool quickly when exposed to air given that decomposition can continue, and they typically do not require external heat sources to ignite, especially when self-heating has occurred. Understanding the dynamics of organic decomposition and the conditions that promote self-heating is essential for effective fire investigation.