Fire Origin & Cause (2nd Edition)
Chapter 2 - Safety During the Fire Cause Determination Process
Test Review

  • Scene analysis (possible hazards) determines what protective equipment will be worn by investigators.
  • Airborne dust particles contain high levels of carbon, which is a carcinogen.
  • Depending on possible exposures, investigators should wear a filter mask rated for particulate filtering or rated for vapor/gas removal.
  • Potential exposures determine the type of protective breathing to be worn by investigators.
  • The most important characteristics of gloves are the protection they provide against heat or cold penetration, and their resistance to cuts, punctures, and liquid absorption.
  • Gloves must fit properly and provide dexterity.
  • Investigators should always wear a hard hat or fire helmet.
  • Structural turnout coats, trousers, and boots are suitable for post-fire activities.
  • Boots should provide adequate toe and midsole protection.
  • Weather permitting, investigators may wear coveralls.
  • Investigators entering hazardous areas should wear a PASS device.
  • Investigators must have a supply of basic first aid equipment.
  • When stabilizing a structure, factors to consider include: fire-damaged structural elements, collapses, and additional water weight from fire fighting.
  • Extinguishing agents such as carbon dioxide (CO2), can exclude oxygen in emergency situations.

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  • Common gases at fire scenes include: carbon monoxide, carbon dioxide, nitrogen oxides, hydrogen chloride, hydrogen cyanide, and phosgene.
  • More fire deaths occur from carbon monoxide (CO) than any other toxic product of combustion.
  • Carbon monoxide is colorless, odorless, and is produced in every fire.
  • Poor ventilation and inefficient burning causes high levels of carbon monoxide.
  • Black smoke is high in particulate carbon and carbon monoxide because of incomplete combustion.
  • Carbon monoxide causes headaches, dizziness, nausea/vomiting, and cherry-red skin (based on exposure).
  • Carboxyhemoglobin is a very stable pinkish red combination of hemoglobin and carbon monoxide that forms in the blood, resulting in loss of blood's ability to combine with oxygen (damages heart/lungs early).
  • Carboxyhemoglobin levels in blood are affected by persons physical condition, age, degree of activity, and length of exposure.
  • It takes years for carboxyhemoglobin to dissipate from the bloodstream.
  • Asymptomatic means "without symptoms".
  • Administering pure oxygen and receiving prompt medical attention are the most important elements of carbon monoxide exposure.
  • Hydrogen chloride (HCl) is colorless and is easily detected by its pungent odor.
  • Hydrogen chloride causes intense eye and respiratory tract irritation (swelling of upper respiratory tract).
  • Hydrogen chloride is released from burning PVC and plastics containing chlorine (common in drug, toy, and general merchandise stores).
  • Hydrogen cyanide (HCN) is a colorless gas with an almond odor.
  • Hydrogen cyanide interferes with respiration at the cellular and tissue level and is a chemical asphyxiant.
  • Hydrogen cyanide is given off when wool, nylon, polyurethane foam, rubber, and paper burn.
  • Hydrogen cyanide levels are high with fires in clothing stores and aircraft cabins.
  • Hydrogen cyanide can cause gasping respirations, muscle spasms, and increased heart rate.
  • Carbon dioxide is the end product of complete combustion of carboniferous materials.
  • Carbon dioxide is non-flammable, colorless, and odorless.
  • Free-burning fires produce more carbon dioxide than smoldering fires.
  • Oxides of nitrogen are nitrogen dioxide and nitric oxide.
  • Nitric oxide readily converts to nitrogen dioxide in the presence of oxygen and moisture.
  • Nitric dioxide is a reddish brown pulmonary irritant (AKA silo gas).
  • Nitrogen dioxide is liberated from pyroxylin plastics when they burn and is common around grain bins/silos.
  • Drafting tools are made of pyroxylin plastics.
  • Oxides of nitrogen are water soluble and turn into nitric and nitrous acids.
  • Oxides of nitrogen in the body are neutralized into nitrites and nitrates which chemically attach to the blood causing arterial dilation, headaches, dizziness, and coma.
  • Nitrogen dioxide is an insidious gas because of irritating effects in the nose and throat can be tolerated even though a lethal dose is being inhaled (delayed effect of several hours).
  • Phosgene is a colorless, tasteless gas with an odor of musty hay.
  • Phosgene is produced when refrigerants, such as freon, burn.
  • Phosgene decomposes into hydrochloric acid when it contacts water (same in lungs).
  • Toxic gas factors at fire include: nature of combustible, rate of heating, temperature of gas, and oxygen.
  • Monitoring devices include: detector tubes, combustible gas indicators, oxygen deficiency, toxic gas, & combination meters, multi-specific gas detectors, and radiation detectors.
  • Atmospheric monitors provide investigators with type of hazard and relative quantity present.
  • Positive pressure ventilation produces a higher pressure inside the structure than outside.
  • Advantages of positive pressure ventilation include: more efficient removal of toxic gases, velocity of air current is minimal, placement of blowers does not interfere with ingress/egress.
  • Pulling electrical meters can result in blinding or explosive arc if done improperly.
  • Rubber footwear should not be relied upon as an insulator.
  • Cameras, sniffers, and other investigative equipment are NOT explosion proof.
  • Applying intensely concentrated lighting to the exterior of a building creates an adjustment problem for the eyes.
  • Power cords should be orange or yellow for portable lighting.
  • Inspect apparatus fuel storage areas at least weekly.
  • Animals that have bitten a person should be secured and impounded for rabies observation.
  • Hepatitis virus can live several days in dried blood spills.
  • Hazardous material is defined by USDOT as "a substance or material, including hazardous substance, that has been determined by the Secretary of Transportation to be capable of posing an unreasonable risk to the health, safety, and property when transported."
  • The priority of investigators at a HazMat scene is self-protection.
  • Placards are diamond-shaped signs affixed to each side of a vehicle and indicate the primary class of material and sometimes the exact material carried.
  • Investigators should observe HazMat scenes from a safe distance and wait for area to be declared safe.

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