We can smell essential oils because they are volatile, meaning they evaporate at room temperature, and we breathe them in. Not all essential oils though are equally volatile – some evaporate quickly, others much slower. You might have heard essential oils referred as top, middle and base notes. This is determined on how quickly they evaporate, or how long the smell ‘lasts’.
When we smell or inhale essential oils, yes, a tiny amount is absorbed through our lungs. While this can certainly have an effect on our body, the intensity is nowhere near as powerful as when essential oils (always diluted) are applied to our skin. In fact, when applied topically (skin) essential oils are absorbed one thousand times more than when inhaled (smelled). The reason being is that they are actually absorbed into our blood via our skin, essentially becoming a part of us.
Let Me Explain Further…
Despite what some cosmetic companies will lead you to believe, many products are unable to be absorbed through the skin due to their chemical makeup.
How Are Essential Oils Absorbed?
Essential oils are transported into the skin through the hair follicle, at the base of which is the papilla or root. Without realizing it, you have probably noticed the papilla when plucking a hair out with tweezers – it’s the black bulb at the end of the hair that's been plucked. The papilla’s job is to attach the hair to the follicle and allow a blood supply to feed the hair. When this happens there is a little gap that allows the essential oil to enter directly into the blood stream. Studies have actually shown that after lavender oil is massaged into the skin, traces of the oil show up in the urine. In other words, the lavender has entered through the skin, into the blood stream and what wasn't used by the body, was filtered by the kidneys and excreted in the urine.
Why Essential Oils Must Be Pure
Knowing that essential oils become a part of our blood stream and are dealt with by our excretory organs like our kidneys and liver, it stands to reason that you would only use a guaranteed source of pure unadulterated essential oil. Organically sourced and grown are preferred. If there are toxins or pesticides in the oil, as there have been found in the oils produced by less ethical dealers, these harmful substances can enter your body. Our bodies have to deal with enough toxic rubbish on a daily basis without introducing more.
Stuff To Make Your High School Chemistry Teacher Proud
The evaporation rate of a substance is determined by the size of the molecule mass (weight). So stands to reason that the lighter they are the faster molecules will evaporate. The more intense the smell. Molecular mass is given in units called Daltons. Almost all essential oil molecules are 300 Daltons or less as this makes them volatile (evaporate).
I’m telling you all this because substances with low molecular mass are also usually able to penetrate the epidermis (top layer of skin), mucous membranes and bacterial cell walls (more on this when we talk about antibacterial qualities of essential oils).
Essential oil molecules are mostly fat-soluble which makes them fat loving. Also known as lipophilic. The measurement scale scientists use for ‘how fat loving molecules are’ is called log P.
A positive (+) log P number shows preference for fat, so all essential oil molecules have a positive log P. Some higher than others.
Which means ... the ability for an essential oil to penetrate the skin depends on both the essential oils’s molecular mass and its log P.
So when you’re applying your essential oil blends to your skin just think about the complexity of the processes happening under your touch.