Essentials of Fire Fighting 6th Edition Firefighter I Chapter 19 — Fire Origin and Cause Determination

Learning Objective 1 Explain ways to recognize obvious signs of the area of origin.

The area of origin contains several pieces of important information. Precise point of origin, ignition Greatest amount of damage, debris Area of origin Potentially lethal concentrations of gas present Monitor air Wear full PPE Assume

Arson – Criminal charges Debris on scene contains fire cause indicators and must remain in place. May be used in court Arson – Criminal charges Courtesy of Donny Howard

Remember from on scene – What you You must control evidence and remember information from the incident as much as possible. Chain of custody Required in legal cases Control evidence See Smell Hear Remember from on scene – What you

CAUTION You should minimize fire suppression and overhaul activities that could destroy important evidence regarding the origin and cause of the fire.

Several factors will influence locating the area of origin and the overall success of the investigation. May be apparent, if not Follow from least damage to most Critical to overall success Identify witnesses Secure scene Note initial scene Incident Commander or fire/criminal investigator Determine point fire started, fire cause Protect or collect evidence Wildland or ground cover fire May require experienced investigator

The search for area of origin at a structure fire begins outside. Courtesy of Donny Howard

You should know actions to take when the origin cannot be determined. Delay overhaul beyond locating, extinguishing fires Protect scene Establish scene security

Preliminary assessment and exterior examination require specific tasks. Exam scene to determine Document, preserve Specific observations

Fire indicators to use: The interior examination begins in the area of least damage and works toward the area of greatest damage. Fire indicators to use: Fire patterns Melted metal, glass Degree of damage Courtesy of Donny Howard

Charring on floors and vertical surfaces can indicate useful information. Where fuel burned in that location Face toward area or point of origin Courtesy of Donny Howard

Area of origin and fire spread factors should be closely examined. Multiple areas of origin Factors affecting fire spread Be aware of general patterns May indicate intentionally set Unintentional may give same appearance Materials in fire’s path Building features, layout Ventilation openings Fire load Fire suppression tactics Activation of suppression systems Call investigator if there is a question

Total structural fire loss presents unique investigation challenges. Courtesy of Donny Howard

Exterior fires involve several different types of materials. Stored materials Debris Trash Rubbish Ground cover or vegetation

Ground cover fires require specific understanding of several concepts. Basic fire behavior Effects of winds Topography Natural fuels on fire spread Burns outward in all directions

Fire burns in equal directions when on flat ground and without wind.

The rate and direction of spread of ground cover fires are affected by several components. Wind direction Wind velocity Terrain/topography Types of fuel Ambient temperature Relative humidity Moisture content of fuel

Ground cover fires require specific understanding of several concepts. Evidence of slower, less intense fire growth Unburned materials Effects of flame on fuels less than at head Area of origin may display Backsides of grass, trunks protected Grass will fall toward area of origin White ash product of more complete combustion Radiant heat affects adjacent fuels

Finding the area of origin for vehicle fires is similar to the structural process. Search for area of origin Interview witnesses, firefighters Examine exterior, interior

Vehicle fires require knowledge and practice of several safety guidelines. Ensure undeployed air bags inoperable Ensure shock absorber bumpers inoperable Hybrid, electric car considerations Do not cut posts that contain restraint systems Know where large capacity or multiple fuel cells may exist Hydraulic system considerations Check trunk area for flammable/ combustibles

WARNING Do not attempt to access or examine a vehicle unless you know how to do so safely.

REVIEW QUESTION What ways can a Firefighter I recognize obvious signs of a fire’s area of origin?

Learning Objective 2 Describe the relationship between fire cause classifications and cause determination.

Fire cause determination is a critical step in the investigation process. Look for Competent ignition source Ignition sequence Determination can Document causes of fire Indicate trends in unsafe behavior Indicate defective equipment, design flaws Indicate malicious, illegal behavior

Open flame, ember, or torch The National Fire Incident Reporting System (NFIRS) reports several causes of fires in structures. Incendiary Open flame, ember, or torch Other heat, flame, or spark Smoking materials (Cont.)

Electrical or lighting equipment The National Fire Incident Reporting System (NFIRS) reports several causes of fires in structures. Lightning, natural Heating equipment Cooking equipment Electrical or lighting equipment (Cont.)

The National Fire Incident Reporting System (NFIRS) reports several causes of fires in structures. Heating, ventilating, and air-conditioning (HVAC) appliances Other equipment Exposure Children playing with matches, lighters, or other ignition sources

There are four types of fire cause classifications. Accidental Natural Incendiary Undetermined Courtesy of Iowa Fire Service Training Bureau. Courtesy of Donny Howard

There are several obvious signs of cause you should look for. Courtesy of Bob Espositio

DISCUSSION QUESTION What are some visual signs that may determine the area of origin for ground cover fire?

Absence of an obvious ignition source can help investigations. Eliminate some causes Focus on other causes

REVIEW QUESTION What is the relationship between fire cause classifications and cause determination?

Learning Objective 3 Recognize signs of arson.

You will need to provide information if an incendiary or undetermined initial cause is indicated. Gather based on Observations Different personnel may perform formal investigation Local or state fire investigators Law enforcement officials (Cont.)

You will need to provide information if an incendiary or undetermined initial cause is indicated. Time of day Weather, natural hazards Manmade barriers People leaving the scene Courtesy of Donny Howard

Additional information should also be gathered to assist investigators. Time of arrival and extent of fire Wind direction and velocity Doors or windows locked or unlocked Location of fire (Cont.) Courtesy of Donny Howard

Additional information should also be gathered to assist investigators. Containers or cans Burglary tools Familiar faces Courtesy of Donny Howard

Conditions should also be observed to provide information for investigators. Unusual odors Abnormal behavior of fire when water applied Obstacles hindering fire fighting Incendiary devices (Cont.)

Structural alterations Conditions should also be observed to provide information for investigators. Trailers Structural alterations Fire patterns Heat intensity Courtesy of Donny Howard (Cont.)

Availability of documents Fire detection and protection systems Conditions should also be observed to provide information for investigators. Availability of documents Fire detection and protection systems Intrusion alarms Location of fire (Cont.)

Equipment or inventory Conditions should also be observed to provide information for investigators. Personal possessions Household items Equipment or inventory Business records Courtesy of Donny Howard

REVIEW QUESTION How can a Firefighter I recognize signs of arson?

Learning Objective 4 Describe the importance of preserving evidence.

Learning Objective 5 Explain techniques for preserving evidence.

Preserving evidence requires understanding certain principles. Responsibility of all at scene Do not determine what is/is not unless qualified Protect everything that looks odd, suspicious

There are several important aspects of protecting the fire scene. Scene security - First Early security measures Restrict scene access Protect potential evidence Minimize suppression, overhaul activities that could destroy information First-arriving investigator May adjust or implement new measures Decision factors May request monitoring of each entrance, exit to document individuals on scene

Establishing a scene perimeter requires specific knowledge. Explosions Structure Courtesy of Ron Moore, McKinney (TX) Fire Department

There are several ways to establish perimeters that are both recognizable and enforceable. Ensure initial larger than needed Ensure visible, recognizable Use law enforcement or firefighters to control

Procedures for criminal investigations also impact scene security practices. Keep entry log Permit access to only those authorized Move personnel to staging area when tasks complete Ensure others always escorted Mark potential evidence to prevent disturbing

There are several techniques used to preserve evidence. Keep evidence untouched, undisturbed Do not gather or handle unless necessary to preserve Document all actions Follow department SOPs (Cont.)

There are several techniques used to preserve evidence. Avoid walking on, cross-contaminating, or destroying Avoid excessive water use Protect footprints, tire marks Close dampers and other openings Leave charred documents Protect documents from air flow

Overhaul operations can be detrimental to an investigation. May destroy potential evidence Delay until origin and cause determined Begin once critical evidence protected

Even when a scene is secure, contamination or spoliation can occur. Courtesy of Donny Howard

Follow local procedures when finalizing operations and investigations. After investigation complete Secure structure, turn over to occupant Perform according to local SOPs Debris removal Follow local protocol May be last activity Prevent rekindle Separate unburned Dump debris where not visible if possible

REVIEW QUESTION What are some techniques firefighters can use to preserve evidence?

Summary One of the most important responsibilities is protecting evidence. Use appropriate caution in the area of origin. A thorough investigation can be conducted to determine the exact cause of the fire.