VOCs

Human breath is mainly composed of nitrogen (~74%), followed by oxygen (~15%), water vapour (~5%) and then carbon dioxide at around 5%. The missing 1% includes argon and small amounts of hydrogen, carbon monoxide and ammonia, followed by an even smaller amount of volatile organic compounds (VOCs).

Consuming food and drinks may affect VOCs; for example, methanol is present in foods such as apples. Garlic, onion, mint, banana and coffee are also shown to emit volatiles at trace concentrations, which have been detected, after ingestion, in a mouth-exhaled breath.

'Coffee breath' has been linked to 3-mercapto-3-methylbutyl formate, which is the compound drawn around the pop-art lady in the drawing.