Guarda Systems | Carbon Monoxide

Carbon Monoxide

Carbon Monoxide Hazards Explained

Carbon Monoxide is an odorless and colorless exhaust by-product of combustion engines. Potentially dangerous exposure can occur before symptoms actually appear.

High exposure in the short-term can include the following key symptoms:

  • Drowsiness
  • Severe headache
  • Dizziness
  • Vomiting
  • Impaired judgement
  • Convulsions, coma and death can occur with acute exposure
The long-term effects of Carbon Monoxide exposure are hardening of arteries and increased risk of heart attack.

US Exposure Limits

The current Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) for carbon monoxide is 50 parts per million (ppm) parts of air (55 milligrams per cubic meter (mg/m(3))) as an 8-hour time-weighted average (TWA) concentration [29 CFR Table Z-1].

The National Institute for Occupational Safety and Health (NIOSH) has established a recommended exposure limit (REL) for carbon monoxide of 35 ppm (40 mg/m(3)) as an 8-hour TWA and 200 ppm (229 mg/m(3)) as a ceiling [NIOSH 1992].

The American Conference of Governmental Industrial Hygienists (ACGIH) has assigned carbon monoxide a threshold limit value (TLV) of 25 ppm (29 mg/m(3)) as a TWA for a normal 8-hour workday and a 40-hour workweek [ACGIH 1994, p. 15].


Sourced from NIOSH Publication # 1996 (from website)
Figure 1. Actual CO concentrations measured inside a 2,332-cubic-foot bathroom with a gasoline-powered, 5-horsepower concrete saw operating (doors open, cooling fan and ventilation running).