Carbon Monoxide and Aircraft

A few years ago, I was flying in a northern community in a turbine aircraft. While the aircraft was on the ground, it was connected to a fuel-burning heating cart. About an hour before departure, I went to the aircraft to prepare for the return flight home. Upon opening the cabin door, I was hit with an overwhelming smell of exhaust. It was evident that something was wrong with the heating cart. It could have had an internal malfunction or the air intake was drawing in exhaust. We aired out the aircraft before re-entering, but even after ventilation, a distinct residual smell of exhaust lingered for the rest of the day. I also developed a strong headache, indicating I had likely been exposed to carbon monoxide (CO).

Photo by Pascal Meier on Unsplash


What is Carbon Monoxide?

Carbon monoxide (CO) is a colorless, odorless, and tasteless gas that is poisonous to humans. While the young, elderly, and those with preexisting health conditions may be more vulnerable, CO can affect everyone at dangerous levels.

CO is particularly hazardous in enclosed spaces where it can accumulate. Many governments recommend or require homeowners to install CO detectors due to the risks associated with faulty furnaces and other fuel-burning appliances. CO is produced when fuels such as oil, wood, natural gas, propane, or kerosene are burned.

Symptoms of Carbon Monoxide Poisoning

The severity of symptoms depends on the level of exposure and the duration. Symptoms can include:

  • Headache
  • Fatigue
  • Shortness of breath
  • Nausea
  • Dizziness
  • Mental confusion
  • Vomiting
  • Loss of muscular control
  • Loss of consciousness
  • Death

Effects of CO at Different Levels

CO Level (ppm) Effects on Humans
35 ppm (0.0035%) Headache and dizziness within 6–8 hours of constant exposure
100 ppm (0.01%) Slight headache within 2–3 hours
200 ppm (0.02%) Slight headache within 2–3 hours; loss of judgment
400 ppm (0.04%) Frontal headache within 1–2 hours
800 ppm (0.08%) Dizziness, nausea, and convulsions within 45 minutes; insensibility within 2 hours
1,600 ppm (0.16%) Headache, increased heart rate, dizziness, nausea within 20 minutes; death in less than 2 hours
3,200 ppm (0.32%) Headache, dizziness, nausea in 5–10 minutes; death within 30 minutes
6,400 ppm (0.64%) Headache, dizziness in 1–2 minutes; convulsions, respiratory arrest, and death in under 20 minutes
12,800 ppm (1.28%) Unconsciousness after 2–3 breaths; death in less than 3 minutes

Implications for Pilots

Most small aircraft use engine exhaust for cabin heat, directing outside air over the exhaust pipe to warm the interior. If there is a leak in the exhaust pipe, CO can enter the cabin. Similarly, fuel-burning heaters can also pose a risk if exhaust leaks occur. While turbine aircraft have a lower risk of cabin contamination (as air is drawn in before combustion), there is still a possibility of CO exposure on the ground when using external fuel-burning heaters.

How to Protect Yourself

The simplest and most effective way to protect yourself is to install a carbon monoxide detector. These devices range from simple colour-changing “dots” to advanced digital detectors that alert you when CO levels exceed safe limits.

What to Do if You Suspect CO Exposure

  1. Leave the Area: If you suspect CO exposure, exit the area immediately.
  2. Eliminate the Source: If it is safe to do so, turn off the suspected source of CO and ventilate the space with fresh air.
  3. Seek Medical Attention: Visit an emergency room or doctor as soon as possible, even if symptoms subside. CO binds to hemoglobin in the blood, and it can take at least 80 minutes on 100% oxygen to reduce CO levels by half.
  4. Do Not Re-enter Until Safe: Only return to the area once it has been declared safe by authorities such as the fire department.

Practical Considerations

  • Safe CO levels ideally should not exceed 20 ppm.
  • For perspective, exposure to car exhaust in heavy traffic can range from 100–200 ppm, and undiluted car exhaust can reach up to 7,000 ppm.
  • Even low-level exposure can have cumulative effects, making detection and prevention crucial.

Final Thoughts

Understanding the dangers of carbon monoxide, knowing how to respond to exposure, and advocating for CO detectors in the workplace are essential steps for pilots and aviation personnel. Remember, carbon monoxide is odourless; you cannot rely on the smell of exhaust as a warning sign. Protect yourself and those around you by staying vigilant.

Sources

Photo by Pascal Meier on Unsplash

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