Blood oxygen level

[dozeydo]

Can anyone tell me how the thing they put on your finger to monitor blood oxygen level works? Also, does anyone know what oxygen levels are ok?

[kempie]

http://www.oximetry.org/pulseox/principles.htm

http://www.psocdeveloper.com/uploads/tx_piapap pnote/an2313_01.pdf

A pulse oximeter reading (SpO2) in the high 90s (i.e. 96%-99%) is considered normal.

[dozeydo]

Kempie - many thanks for a very helpful answer!