I use a "death dot" in my airplane. I think it is adequate. My assumption is that most, if not all, CO leaks begin slowly, then grow over time. For instance, an exhaust crack starts small then grows into a larger crack. Hopefully, that gives me the opportunity to notice the dot discoloring before the leak becomes large enough to cause serious problems.
The OSHA level for a 'shift length' exposure to CO is 50ppm. The 5 min level is 200ppm.
In Aviation consumers test, the dot detectors did work to change colors at levels of 200 to 400ppm.
Low level exposures (10-100ppm) have been shown to cause temporary neuropsychological impairment. It is similar to the effects of altitude related hypoxia.
This is the table from Wikipedia, I would rather quote a primary source but the numbers sound about right:
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35 ppm (0.0035%) Headache and dizziness within six to eight hours of constant exposure
100 ppm (0.01%) Slight headache in two to three hours
200 ppm (0.02%) Slight headache within two to three hours; loss of judgment
400 ppm (0.04%) Frontal headache within one to two hours
800 ppm (0.08%) Dizziness, nausea, and convulsions within 45 min; insensible within 2 hours
1,600 ppm (0.16%) Headache,
tachycardia, dizziness, and nausea within 20 min; death in less than 2 hours
3,200 ppm (0.32%) Headache, dizziness and nausea in five to ten minutes. Death within 30 minutes.
6,400 ppm (0.64%) Headache and dizziness in one to two minutes. Convulsions, respiratory arrest, and death in less than 20 minutes.
12,800 ppm (1.28%) Unconsciousness after 2-3 breaths.
Death in less than three minutes.
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The reasons not to use a 'death dot' are imho that:
- it won't detect the lower level exposures that are hazardous in an aviation context.
- it won't start to rattle and beep at the higher exposures that have the potential of killing you in an hour.
