Some of our ICEBOX customers have asked about ventilation so we tested for carbon monoxide levels with the following conditions. Here are our findings.
For ventilation we had a 3 inch gap below a door which was a hanging poncho and a 1 inch diameter hole in the center of the ceiling.
With a lantern and stove burning and using ISO-butane fuel the CO level was below 5 ppm.
With a burning stove using Coleman fuel we had readings of 22 ppm 12 inches below the ceiling and 20 ppm 10 inches above the floor. The levels were well below the OSHA levels labeled as hazardous.
The Occupational Safety and Health Administration (OSHA) standard for exposure to carbon monoxide prohibits workers' exposure to more than 35 parts of the gas per million parts of air (ppm), averaged over an 8-hour workday. There is also a ceiling limit of 200 ppm (as measured over a 15-minute period).