Scientists are working on diagnostic techniques that could sniff out chemical compounds from breath, sweat, tears and other bodily emissions and that act as fingerprints of thousands of diseases.
When you smell a perfume, encounter the scent of flowers or spices, or suffer through a whiff of pollutants, what your body is actually sensing are volatile organic compounds, chemicals that have a low boiling point and thus evaporate easily. That is, they are volatile, and these chemicals as a group are called volatile organic compounds or VOCs.