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CO
Exposure
Effects of Exposure
to Carbon Monoxide
at this level
Source/comment
0 ppm
No effects, this is the
normal level in a
properly-operating heating
appliance
No carbon monoxide should be detected in
residential properties. Possible brief
technical exceptions occur.
9 ppm
Maximum allowable short
term exposure
ASHRAE
10 - 24 ppm
Investigation needed to find
source;
Health effects on humans uncertain.
25 ppm
Maximum allowable TWA
exposure limit
OSHA. Used in personal CO alarms.
35 ppm
Maximum allowable
workplace exposure limit for
an 8-hour work shift
NIOSH (40 hour work week)
50 ppm
Maximum allowable
workplace exposure limit for
an 8-hour work shift
OSHA (40 hour work week)
125 ppm
Workplace alarm must
sound
OSHA
200 ppm
Evacuate the area
immediately.
Exposure at 200 ppm of CO causes
dizziness, nausea, fatigue.
400 ppm
Evacuate the area.
3 hour exposure may be fatal.
800 ppm
Evacuate the area.
2-3 hour exposure causes convulsions,
loss of consciousness, death.
1200 ppm
Evacuate the area..
Revised IDLH
