Your Health is at Risk: HYDROGEN CYANIDE AND CARBON MONOXIDE POISONING Where do HCN and CO come from? ✦ HCN and CO are byproducts of combustion: flaming and smoldering, ventilation-controlled and fuel controlled. ✦ Plastic and synthetic polymers burn 2-3 times hotter and faster with quicker flashovers. How do HCN and CO affect you? ✦ They are both cellular asphyxiants! SMOKE RECOGNITION ✦ HCN shuts down the aerobic pathway, creating lactic acidosis and other toxic 1. Turbulent smoke that fills a box: substances in tissues and organs. READING SMOKE • Imminent flashover. ✦ CO hemoglobin bonds 200-300 times that of oxygen. Its half life is 2-5 hours as 2. Fast brown smoke from structural concentration decreases. areas: ✦ Acute exposure can result in disorientation, • Unfinished wood ready to ignite. weakness, headaches, or fainting. • Warning sign of collapse in ✦ Chronic exposure can result in respiratory lightweight wooden buildings. issues, cardiac problems, neurological How to Make syndrome, or thyroid gland enlargement. 3. Same color/same speed from How can you protect yourself? multiple openings: Tactical Decisions ✦ Be aware, use your air! • Beware! Deep-seated fire in walls, ✦ Use atmospheric monitoring gas detection. floors or basement. ✦ Conduct post-fire decontamination in an • Early warning sign for smoke (including Nomex hoods). explosion. ✦ Engage in department-wide education to 4. Dirty white smoke with speed: promote awareness of the dangers of HCN Uncontrolled and CO exposure. • Hot fire but smoke has been filtered by distance or resistance. Environment 5. Thin black fast smoke: • Flame-driven and well-ventilated. 6. Thick black fast smoke: • Heat event with limited ventilation. • Caution: Explosive environment!

Source: Dodson, David W. Fire Department Incident Safety Officer. 2nd Edition. Delmar Learning, 2007. (c) 2012 Rick Richford Cover Photo: Wei O’Connell (tianphoto) (c) 2006. Reading smoke is not absolute. Smoke is dynamic, usually changing from good to INVENTORY & COMPARE SMOKE ATTRIBUTES worse. Reading smoke begins with the READING 4 BASIC SIGNS OF SMOKE QUALITY first-arriving apparatus. CAN HELP PREDICT WHAT WILL HAPPEN NEXT Comparing smoke issuing from various openings of similar size is the key. 1. VOLUME tells very little about the fire, 4. COLOR shows the stage of heating and Read the smoke and not the flames. but tells much about how fuel has helps find the location of the fire. (Flames are end products of smoke.) off-gassed within a given container. A. White smoke comes from clean white 3-STEP SMOKE ASSESSMENT A small volume of smoke coming from a moisture from the early state of heating very large structure (e.g., a big retail store of any material (smoke should be slow 1. Compare the volume, velocity, or warehouse) can indicate a serious fire. and laminar). density, and color of smoke from various openings. 2. VELOCITY/FLOW SPEED is the #1 B. Dirty white smoke can mean early 2. Factor in building and weather warning sign of an impending flashover. pyrolysis of plastic (slow smoke) or a hot fire far away (fast smoke that has influences: A. Laminar (smooth smoke) indicates been filtered by distance or resistance). • Consider container size and number the structure is absorbing heat. C. Tan/brown smoke indicates unfinished of smoke vent points. A large B. Laminar smoke that falls outside is wood that is pyrolizing just prior to building with multiple smoke exit pushed by volume (not heat). points can indicate a large fire. Do ignition (e.g., wood framing and not rely on “light smoke showing.” ➡ Compare various smoke velocities to trusses). determine the location of the fire. • Subfreezing temperatures can ➡ Beware! This type of smoke is a change dark smoke to white smoke. Look for the fastest smoke coming collapse warning sign in Cold air causes smoke to lose ➡ velocity and heat more quickly. from the most restrictive opening. lightweight wood construction. That’s likely where the fire is. 3. Gauge the rate of change: D.Black smoke comes from materials heated to the fullest extent, regardless • Determine how fast smoke 3. DENSITY indicates the color of smoke, of the type of materials ignited. conditions are improving or the quality of burning, and the severity of i. Flat black means mostly worsening. Seconds vs. minutes are the event. critical indicators. carbon-infused smoke from • If smoke density and color worsen, A. The thicker the smoke, the more serious heating. likely a hostile spread event. the chance of smoke ignition ii. Glossy or rich/deep black increases. B. Air sucking into thick smoke smoke is mostly hydrocarbon- • If smoke density is thinning, the fire means a vent-limited fire that is infused smoke from the serious may have found air and is burning likely to grow explosively. heating or burning of plastic and off the smoke. other petroleum products.