Carbon Monoxide Detection Levels
How much Carbon Monoxide is too much?
Health effects can vary significantly due to age, sex, weight, overall state of health. CO is measured in Parts per Million or PPM; out of a million molecules of air, how many are carbon monoxide. The following list relates to non-structure fire generated CO.
12,000 PPM Death within 1 – 3 minutes.
1,600 PPM Nausea within 20 minutes, death within 1 hour
800 PPM Nausea and convulsions – death within 2 hours
400 PPM Frontal headaches within 1-2 hours; life threatening within 3 hours; UL 2034 alarms should sound within 15 minutes.
200 PPM NIOSH (National Institute for Occupational safety & Health) A worker shall not be exposed to more than this amount.
150 PPM UL Listed 2034 CO alarms must respond within range of 10 to 50 minutes this or higher.
70 PPM If CO at this level for 4 hours, UL 2034 alarm should be sounding.
50 PPM Maximum average level for continuous exposure in an 8 hour workday per U.S. federal law.
36-99 PPM This is excessive levels and there are foreseeable health hazards. Suggest a medical alert and health consultation especially if levels displayed are chronic conditions. Advise use of air packs. Ventilation required and source discovery testing recommended.
25 PPM A common level for the use of self contained breathing apparatus by emergency responders. Also an 8 hour time weighted exposure limit prescribed by ACGIH (American Conference of Governmental Industrial Hygienists)
10-35 PPM Marginal – Small children, elderly, and those suffering respiratory or heart problems are cautioned if these are chronic exposure concentrations. May increase heart stresses.
9 PPM This concentration or higher is often measured around busy city streets & intersections. ASH RAE (American Society of Heating, refrigeration and Air Conditioning Engineers) The maximum allowable concentration for continuous (24hr) exposure. The ventilation air shall meet the outdoor air standard referenced to EPA (Environmental Protection Agency) at this level or lower as an ambient outdoor air quality goal as averaged over 8 hours. (A 9 PPM increase over an outside measurement is a common action level if this difference is coming from an inside source. Some jurisdictions require a fuel shut off.)
1-9 PPM It may be difficult to avoid those often occurring spikes in transient or chronic CO levels without life-style changes. Technicians should use test instruments calibrated to the manufacturer specifications. It is recommended that the technician also study up and become familiar with the manufacturer’s sensor capabilities and what type of gases or conditions might interfere with accurate testing. There are good test products on the market but you must pay attention to their factual capabilities and restrictions.