Call Carew Heating and Cooling for reliable AC replacement in Watertown WI.
Trane AC service in Oconomowoc WI is our speciality.
Trane AC service in Oconomowoc WI is our speciality.
(920) 262-2288
1104 S. 10th St.
Watertown, WI 53094
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Allowable Exposure Levels to Carbon Monoxide

Allowable (Legal) Limits for Carbon Monoxide

Occupational Safety & Health Administration, USA (OSHA) (for industrial situations) -

Permissible Exposure Limit (PEL, by TWA) - 50 ppm, 8 hrs.
Old PEL Standard (by TWA) - 35 ppm, 8 hrs.
Threshold Limit Value (TLV, by TWA) - 25 ppm (29 mg/cu. m)
(recommended by American Conference of Governmental & Industrial Hygienists ACGIH)
Ceiling (max. value, 15 min.) - 200 ppm (229 mg/cu. m)

MI Occupational Safety & Health Administration (MIOSHA) -

PEL (Industry, by TWA) - 35 ppm, 8 hrs. (38.5 mg/cu. m)
PEL (Construction, by TWA) - 50 ppm, 8 hrs. (55 mg/cu. m)
Ceiling (max. value) - 200 ppm (229 mg/cu. m)

Environmental Protection Agency, USA (EPA) -

Domestic, outdoor air, all ages (TWA) - 9 ppm*, 8 hrs.
Domestic, outdoor air, all ages (TWA) - 35 ppm, 1 hr.

World Health Organization (WHO) -

Domestic, outdoor air, all ages (TWA) - 9 ppm*, 8 hrs.

American Society of Heating, Refrigeration & Air Conditioning Engineers (ASHRAE) -

Indoor air (leakage at a heat register) - 9 ppm

American Gas Association -

Indoor air (leakage at a heat register) - 15 pm


TWA - Computed by making measurements at intervals over 8 hours, then adding the sums of the concentrations and the intervals, and dividing by 8 hours (480 min.). * Based on several published studies of people with coronary ischemic disease showing ECG changes during moderate exercise when breathing concentrations of CO giving 3% COHb.
1104 S. 10th St. • Watertown • WI • 53094 • (920) 262-2288