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CO
2
Levels and Guidelines
IMPORTANT LIABILITY NOTE
The CO
2
guideline data provided here is meant for informational
purposes only and is not intended as a direct recommendation
from Extech Instruments or FLIR Systems. The user must take full
responsibility when determining how this information is to be
used.
Non-Enforced Reference levels
250 - 350 ppm – background (normal) outdoor air level
350- 1,000 ppm - typical level found in occupied spaces with good
air exchange.
1,000 – 2,000 ppm - level associated with complaints of
drowsiness and poor air.
2,000 – 5,000 ppm – level associated with headaches, sleepiness,
and stagnant, stale, stuffy air. Poor concentration, loss of
attention, increased heart rate and slight nausea may also be
present.
>5,000 ppm – Exposure may lead to serious oxygen deprivation
resulting in permanent brain damage, coma and even death.
Regulatory exposure limits
ASHRAE Standard 62-1989: 1000ppm: CO
2
concentration in
occupied building should not exceed 1000ppm.
OSHA: 5000ppm: Time weighted average over five 8-hour work
days should not exceed 5000ppm
Building bulletin 101 (Bb101): 1500ppm. UK standards for
schools say that CO
2
averaged over the entire day (i.e. 9am to
3.30 pm) should not exceed 1500ppm.
Germany, Japan, Australia, UK: 5000ppm, 8 hours weighted
average occupational exposure limit is 5000ppm.
