The Effect of Altitude on the COHb Curve

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NFPA’s requirements for installing carbon monoxide equipment relies on Carboxyhemoglobin (COHb) curve calculations for assumptions of equipment installation. However, at higher elevations (10,000+ ft), the committee has learned that listed equipment performs differently than at sea level. This raises the question of whether the COHb curve in humans is the same at high elevations than at lower altitudes. If it is different, installation instructions may need to be adjusted for higher elevations.

In addition, OSHA states that people at high altitudes (10,000+ ft) are more susceptible to carbon monoxide poisoning. In Carbon Monoxide and Human Lethality: Fire and Non‐Fire Studies, edited by M.M. Hirschler, states “When persons at high altitude are exposed to low concentrations of CO, symptoms are experienced at much lower blood concentrations and the effects are more severe.”

The committee needs more definitive, quantitative data in order to determine whether or how installation requirements should respond to this medical fact.

Research Goal: The objective of this research is to provide the relevant NFPA Technical Committee with information relating to the impact of altitude on COHb curve to serve as the technical basis for CO warning equipment installation requirements.

Download the project summary. (PDF, 107 KB)