Table 1

Atmospheric and partial pressures of oxygen at different altitudes

Altitude		Barometric pressure		Atmospheric pO₂		Inspired pO₂*
Metres	feet	kPa	mm Hg	kPa	mm Hg	kPa	mm Hg
*Inspired oxygen pressure is calculated from: oxygen fraction in inspired air × [atmospheric pressure − saturation pressure of water at 37°C (6.28 kPa/47.1 mm Hg)].
The barometric pressure in kPa indicates the proportion (%) of inspired oxygen at that altitude compared to sea level; for example, at 3000 m, there is roughly 70% oxygen of that at sea level.
Aircraft cabin pressures are equivalent to those found at 1530–2440 m (5000–8000 feet), and serious altitude related problems usually occur >3000 m.
0	0	100	760	21	159	20	150
1000	3280	90	674	18.9	142	17.4	132
2000	6560	80	596	16.8	125	15.4	115
3000	9840	70	526	14.7	111	13.4	100
5000	16400	54	405	11.3	85	10.0	75
8000	26240	36	267	7.6	56	6.2	46
10000	32800	26	198	5.5	42	4.2	32