Essential oils are extremely volatile meaning they evaporate and diffuse into the air quite easily, allowing you to simply breathe them in and still achieve a fairly strong medicinal effect. This would look like opening the top of the bottle of the essential oil, holding it under your nose and taking a deep inhalation. You can also put a few drops of the essential oil into your palms, rub them together, and then hold them over your face while taking a few deep breaths. Beyond that you can also purchase an essential oil diffuser, which is a special machine that causes the essential oil to become an aerosol, meaning that it evaporates the medicinal compounds in the oil into the air to be breathed in directly when you are near the diffuser (We have had a good experience with this diffuser—it’s stylish, quiet and produces a strong fragrance that fills the room). A good diffuser can easily fill an entire room with a powerful scent of the essential oils making it a good way to stay relaxed while you are at the house and to actually take in a fairly large amount of medicinal compounds in a safe and consistent manner.
Supercritical carbon dioxide is used as a solvent in supercritical fluid extraction. This method can avoid petrochemical residues in the product and the loss of some "top notes" when steam distillation is used. It does not yield an absolute directly. The supercritical carbon dioxide will extract both the waxes and the essential oils that make up the concrete. Subsequent processing with liquid carbon dioxide, achieved in the same extractor by merely lowering the extraction temperature, will separate the waxes from the essential oils. This lower temperature process prevents the decomposition and denaturing of compounds. When the extraction is complete, the pressure is reduced to ambient and the carbon dioxide reverts to a gas, leaving no residue.