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Carbon Monoxide Poisoning

Introduction:

  • Carbon Monoxide, chemically abbreviated as CO, is one of the most common and toxic of substances in the aviation environment
  • Due to its properties as a colorless, odorless, and tasteless gas, it can quietly build, resulting in deadly consequences
  • It is incumbent on the pilot to conduct a thorough preflight which includes the exhaust/heating components to spot irregularities
  • On this page we will go over the sources, detection, and the symptoms which can cue a pilot into the existence of CO poisoning
  • Lastly, and most importantly, we will discuss immediate action which must be taken to treat those symptoms once discovered

Sources of Carbon Monoxide:

  • CO is a by-product of the incomplete combustion of carbon-containing materials, such as aviation fuel
  • While Carbon Monoxide poisoning can occur with or without environmental control operating, heating units are the most likely source of the problem
    • Most heaters in light aircraft work by air flowing over the manifold
    • Use of these heaters while exhaust fumes are escaping through manifold cracks and seals is responsible every year for several nonfatal and fatal aircraft accidents from carbon monoxide poisoning
  • It is possible to have a large amount of CO in your blood just by your environment to include polluted air and being around smokers, thereby reducing your tolerance before takeoff

Carbon Monoxide Poisoning Symptoms:

  • Compounded with additional cues, knowing the symptoms, and recognizing them in your passengers, can be a key indicator
  • Carbon Monoxide has an affinity of 240 times that of oxygen which means it will more readily attach itself to your blood cells
  • Low concentrations over time can produce high blood concentration impeding the bloods ability to transport oxygen
    • As little as 10% Carboxyhemoglobin (Carbon Monoxide in the blood) can decreased peripheral and night vision
  • Symptoms will mirror that of hypoxia as an increase of CO in the blood implies you are actually suffering from hypemic hypoxia
  • Victims could expect: [Figure 1]
    • Sense of pressure in the head
    • Drowsiness
    • dizziness
    • Roaring/ringing sensation of the ears
    • Confused and unable to think clear
    • Drunk appearance
    • Vomiting
    • Incontinent
    • Convulsions
    • Bounding pulse
    • Cherry red lips
    • Dilated pupils
    • Incapacitation

Carbon Monoxide Symptoms
Figure 1: Carbon Monoxide Symptoms

Immediate Action and Treatment:

  • Identify possible sources and attempt to isolate them
    • After removal from CO source, only about 0.5% is removed from blood every 4 hours
  • Use 100% oxygen and open windows to circulate fresh air
  • Monitor for further respiratory distress
    • Tell ATC that you suspect CO poisoning
    • Declare an emergency if you feel the situation warrants
  • Land as soon as possible!
  • If symptoms are severe or continue after landing, medical treatment should be sought
  • Once the situation has been resolved, have the aircraft inspected by a certified mechanic before its next flight
Aircraft Carbon Monoxide Detector
Figure 2: Carbon Monoxide Detector
Aircraft Carbon Monoxide Detector
Figure 3: Hand-Held Carbon Monoxide Detector

Carbon Monoxide Detection:

  • Due to its result from incomplete combustion, there will usually be odors or colors which can provide cues
    • Example: smelling exhaust is an indication of a leak and possible contamination
  • Since Carbon Monoxide is odorless it may be difficult to detect Carbon Monoxide until you or your passengers are experiencing symptoms, at which point any delay can be life threatening
  • Therefore, Carbon Monoxide detectors are cheap insurance which you would rather have and not need, than need and not have
    • Choosing a Carbon Monoxide Detector:

      • As demonstrated in the case studies, carbon monoxide is a life threatening poison
      • Carbon Monoxide detectors come in many designs but generally speaking you'll have the choice of either passive or electronic detectors
      • Passive Detectors:

        • A passive detector, such as the Quantum Eye Carbon Monoxide Detector are the most basic choice [Figure 2]
          • Advantages:
            • Low cost
            • Works independent of electrical power
          • Disadvantages:
            • Indicator must be monitored as it will not produce an alarm
            • Must be attached to something in view
      • Electronic Detectors:

        • Electronic detectors such as the Pocket CO Carbon Monoxide Detector are the more advanced types of detectors [Figure 3]
          • Advantages:
            • Audible alarms when carbon monoxide rises
            • Convenient enough to be carried at home or in a vehicle
          • Disadvantages:
            • Generally more expensive than passive detectors
            • Requires batteries

Case Studies:

Carbon Monoxide Prevention:

  • The easy statement is to follow appropriate maintenance procedures
  • More than that however, is to check potential sources prior to every flight

Conclusion:

  • Carbon Monoxide Poisoning in a silent killer who's risk can be mitigated through a few simple steps
  • After CO poisoning, it can take up to 24 hours to recover
  • Especially in winter months, refresh your knowledge on Carbon Monoxide and conduct an extra thorough preflight
    • Remember, the heater system may have gone unused for months
  • Additionally, ensure the Carbon Monoxide detector is in serviceable condition
  • For more information, see the Federal Aviation Administration (FAA) brochure called Carbon Monoxide: A Deadly Menace

References: