Table 3.

Major volatile organic compounds present in the breath of healthy individuals [47].

Compound	Concentration
Water vapor	5–6.3%
Nitrogen	78.04%
Oxygen	16%
Carbon dioxide	4–5%
Hydrogen	5%
Argon	NS
CO	0–6 ppm
Ammonia	0.5–2 ppm
Acetone, methanol, ethanol	0.9%; <1 ppm
Hydrogen sulfide	0–1.3 ppm
NO	10–50 ppb
Carbonyl sulfide	0–10 ppb
Ethane	0–10 ppb
Pentane	0–10 ppb
Methane	2–10 ppm