A simple experiment can show you the importance of our noses. Hold the nose and try to tell foods apart. Its really hard! Our sense of smell is closely allied to our sense of taste. Our noses are excllent detectors of volatile organic compounds. The largest users of essential oils is the flavour and fragrance industries. To create consistent aromas essential oil contituents are used either obtained from the whole essential oils or synthesised.
With any volatile organic compound safety must be borne in mind and considerable research is devoted to establishing safety guidelines.