What are safe levels of CO and CO2 in rooms?


250-400ppm Normal background concentration in outdoor ambient air
400-1,000ppm Concentrations typical of occupied indoor spaces with good air exchange
1,000-2,000ppm Complaints of drowsiness and poor air.
2,000-5,000 ppm Headaches, sleepiness and stagnant, stale, stuffy air. Poor concentration, loss of attention, increased heart rate and slight nausea may also be present.
5,000 Workplace exposure limit (as 8-hour TWA) in most jurisdictions.
>40,000 ppm Exposure may lead to serious oxygen deprivation resulting in permanent brain damage, coma, even death.


9 ppm CO Max prolonged exposure (ASHRAE standard)
35 ppm CO Max exposure for 8 hour work day (OSHA)
800 ppm CO Death within 2 to 3 hours
12,800 ppm CO Death within 1 to 3 minutes