By Alison Campbell 08/04/2019

A story about essential oils being used in classrooms hit the headlines this week.

It described how an Auckland primary school had put diffusers into 20 classrooms, using oil blends that would supposedly “stop the spread of viruses and keep children focused at school.” A parent subsequently used the threat of a legal injunction to stop this practice, at least for the moment.

Now, some of the skills children are supposed to gain at school are those used in critical thinking. It would be nice to see the school management applying the same skills to decisions like this¹. I mean, is there actually good evidence that these products actually do what’s claimed for them? Do they “stop the spread of viruses” or “keep children focused at school”? (Trialling them in one classroom and relying on the teacher’s observations is not sufficient, given how susceptible the latter is to confirmation bias.)

There’s certainly a lot of woo claimed for the oils! One of my first hits was this one, which is basically an advertorial and appears to be written by a teacher who has definitely not applied critical thinking skills to the claims they are making. I can safely say this because (among other things) they state that using an essential oil diffuser will increase the oxygen levels in the classroom!!! (I did comment there; who knows how long that will last?)

Searching PubMed using the string <essential+oils+viruses> yields just 195 results. (Replacing ‘viruses’ with ‘rhinoviruses’ – the ones that cause colds – returned precisely zero hits.) The studies listed on the first page are largely in vitro studies (ie looking at the effect of the oils on cells in petri dishes), plus some looking at the value of the oils as surface sanitisers. The papers that come up on a Google Scholar search are the same; they look at cytotoxicity in vitro, on surfaces, and (sometimes) in animal studies. Yes, these products will definitely kill pathogens in the petri dish & on hard surfaces – most essential oils are strongly cytotoxic². It’s a big leap from there to claim that airborne oil particles will kill viruses and bacteria in the classroom.

Of course, the other question that should have been asked before the oils were used in the classroom was, do they have any documented negative impacts on health? A subsequent Herald article was based on feedback from neurologist Gareth Parry, who noted that “eucalyptus oil and rosemary oil were just two of 11 essential oils that potentially caused seizures”. There’s been research on this for quite some time (though not by the company providing the oils; not that I could see on their website, anyway) and it goes back a long way – see here and here, for a couple of those earlier studies. (Yes, these document topical and/or internal use, not airborne.)

However, more recent studies are also not exactly promising. This paper looks at the levels of the oils’ active components when evaporated (not diffused³), their concentrations in the room’s air were measured, and their antimicrobial activity assessed. The researchers found that

The anti-microbial activity on airborne microbes, an effect claimed by the use of many essential oils, could only be found at the first 30–60 min after the evaporation began as the highest levels of volatile components in these essential oils appeared to emit into the air…

They documented high emissions of a class of compounds called terpense, and commented that these

warranted … further examination for their health implications, especially for their potential contribution to the increasing indoor levels of secondary pollutants such as formaldehyde and secondary organic aerosols (SOAs) in the presence of ozone.

Not exactly a strong endorsement, then.

Finally, the oils used by the Auckland school were supplied by the company doTERRA, described in the Herald article as a multi-level marketing company, and the fact that the school intended to have “an information evening about the product” was a bit of a red flag to me. Perhaps I’m a cynic, but I wonder if a sales push would have been a part of this. Interestingly, while doTerra’s website strongly implies that these oils will have a positive impact on the health and focus/alertness of teachers and students, it also carries the (small print) disclaimer that (my emphasis)

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.


¹ Actually, I’d ask the same of the Ministry of Education, since in the Herald article, the school principal states that they received clearance from the Ministry to use the oils & diffusers.

² lots of things kill cells in petri dishes

³ since of oil’s components into the air is slower when diffused, I did wonder how likely it would be that any biologically-active concentrations would be achieved at all by a classroom diffuser.

The post essential oils in the classroom: a rose (or other flowers) would smell as sweet appeared first on BioBlog. Featured image: Cushy Spa, Flickr CC.

0 Responses to “Essential oils in the classroom: a rose (or other flowers) would smell as sweet”

  • I’m afraid your own arguments are more based in biases than critical thinking. While I agree that there are many exaggerated claims and misinformation about essential oils out there, a general dismissal of their benefits is completely maligned. On the one hand you imply that they don’t actually work, on the other hand you imply that they are dangerous. Are they powerful enough to cause seizures, but so impotent they have no other effects on our body’s biological or physiological mechanisms?

    Also, you use the fact that there are only 195 results on PubMed when searching for essential oils + viruses as a means to dismiss the antiviral properties of essential oils. You then go on to point to research on essential oils causing seizures. A quick PubMed search on essential oils + seizures yields 74 results (far fewer than the viral studies), where at least 80% of the results on page one are articles documenting anti-convulsant properties of essential oils.

    Again, I can see why folks with no background in essential oils have a knee jerk reaction to their touted benefits when there are plenty of exaggerated claims out there. But let’s not throw the baby out with the bath water, here.

    • Thanks for your comment.

      A quick search on pubmed for “essential oils + seizures” does indeed yield 74 results. The great majority of those on page one are of studies in rats & mice. This is not in any way support for using the oils in the classroom.

      If we add “convulsions” to the search string the results are not supportive of the claim that they are anticonvulsant in humans. Instead, they strongly support the claims of the neurologist I mentioned in my post.

  • Sheesh! That’s some pretty aggressive marketing tactics on display. Thanks, Grant, excellent find.

  • Thank you for posting your research. I had been considering using an essential oil diffuser in my middle school classroom because
    1) The room doesn’t have a window (it’s the old computer lab, so there is an independent A/C) and middle schoolers have all sorts of different aromas & odors to contribute. I refuse to give my students unlimited access to Febreeze if they won’t let me keep the classroom door open more often.

    2) I vaguely recalled some anecdotal report of giving students peppermints to suck on before a test improved concentration. I wanted to see if having peppermint and orange scents would result in more students sitting up/trying to connect during lessons

    3) The (possibly unrealistic) hope that with a definitive scent in the room, the use of “fragrant” body sprays would be greatly diminished because either no one will be able to smell those sprays or the scent clash would be too offensive for a student to repeat the trial.

    I’ll continue my inquires with my school & the parents on if there are any personal opinions for/against the practice.

    • Hi Lisa – from what you’ve said, it sounds as if something nice-smelling would make things more pleasant – from an odour perspective – in your classroom 🙂