The purpose of this study is to validate the SpO2 accuracy of pulse oximeter equipment in comparison to "gold-standard" measurements of blood SaO2 by a CO-oximeter

Inclusion Criteria:

• Subjects participate in the study on a voluntary basis
• All subjects should be in good health at the time of the study. Unless specified otherwise in the protocol, the following values could be applied: COHb<3 %, MetHb<2 %, ctHb>10 g/dl;
• Inclusion criteria should serve the purpose of the study

Exclusion Criteria:

• Smokers or individuals exposed to high levels of carbon monoxide that result in elevated carboxyhaemoglobin levels, unless specific dyshaemoglobins are called for in the study protocol.
• Individuals subject to conditions that result in elevated levels of methaemoglobin, unless specific dyshaemoglobins are called for in the study protocol.
• Subjects who would be placed at undue medical risk associated with any procedures called for in the protocol (e.g. arterial cannulation or hypoxia).
• Age: young person and that of more than 50 years old.

healthy volunteers who consent to induced hypoxia and arterial blood sampling as part of the experimental procedure