You are probably wondering, is diffusing "unsafe"? It can be under certain circumstances. You may have heard the phrase, "Children are not little adults."
This is because there are vast differences in their oxygen intake, for example. Did you know that, on a pound-for-pound basis, children breathe more air, drink more water, and eat more food than adults?  Did you also know, an infant breathes more than two times faster than an adult?  They breathe 50% more air in proportion to their weight than adults. 
Exposures are more significant in a child's body than they are in an adult's. If children and adults are vastly different in terms of the air intake, this could be why the suggestions for diffusing are a little different. I referenced a few of the many sources below that I found on this topic. Granted, most of them are topics of children being exposed to toxins in their environment, but some essential oils can be harmful to kids. I felt these sources had some excellent explanations on oxygen intake/inhalation.
Aromatherapy is a wonderful outlet for a variety of support. Aromatherapy can be used orally (which is another topic on its own), dermal absorption (topical use), and by inhalation. One means of inhalation is by diffusion or indirect inhalation. Diffusion or indirect inhalation can affect/expose a room full of people where direct inhalation is to a single person.  I have even heard the term "ambient inhalation" in one of my aromatherapy courses, which means inhaling essential oils that are diffused into the air.
The topic of diffusion safety, I feel, never gets discussed enough. There are descriptions of the differences in inhalation versus diffusion, but the point being, it is still going through your airways into your body. The focus of this blog is on safe diffusing. This blog post may be longer than I wanted, but it is important! So stay with me. Direct Inhalation (personal inhalers) will be a separate blog post in the future.
Diffused (indirect inhalation) essential oils most likely won't cause a toxic/harmful reaction. A possible toxic reaction could occur if a person were confined in a non-ventilated room, with the room's temperature very high. The diffuser would need to be constantly running until the room's air was saturated with essential oils.  This is a worst-case scenario, and again, very unlikely. Someone could still have mild reactions or sensitivity to the essential oils around them, and we need to be aware of what that reaction would look like.
The effects of long-term environmental fragrancing (such as diffusing) with essential oils are unknown and could lead to sensitivity.  If you feel any discomfort or start to get a migraine, mild headaches, lightheadedness, agitation, nausea, sneezing, a tickle in your throat, or start to cough, you may want to back off on your number of drops, the length of time you are diffusing, or both. This can also account for the size of your space you are diffusing in. At this point, turn off your diffuser, open up some windows, and air out your area to start over at another time. If you have an open space, with its ability for ventilation, you should have no issues with the number of drops, but possibly it is more so with the length of time with your diffusion. It would be best to keep in mind adaptation and habituation when diffusing essential oils for an extended length of time. This is why there are suggestions for diffusing time limits. 
Diffuse with a purpose
Essential oils can be expensive; you should try to achieve a specific therapeutic effect regarding diffusing. Inhaling essential oils through diffusing can offer support for many things. I will do a separate Blog next time on the benefits of diffusing.
Diffusing for too long could also have the opposite effects for the purpose of your diffusion.  Furthermore, just like certain scents can bring back a good memory, they can also bring about a bad one. Make sure you pay attention to that if you have guests over and are not enjoying the uplifting aroma you are trying to create.
Diffusing for Children
When diffusing for children, you don't need that much essential oil. It is half the amount or less that you, as an adult, would use. It is also best not to diffuse in their rooms while they are sleeping. The best method for children is to put the diffuser on for 15 mins before their bedtime. Shut off the diffuser, wait at least 15 mins to place your child in their bed. Remember what I have mentioned above on the oxygen intake of children. They will get just what they need from the essential oils lingering in the room after you shut off the diffuser. You do not need to continually diffuse throughout the night for your child to get the full benefits of essential oils.
Another option for children, which is the ideal solution for infants, is to diffuse hydrosols. Hydrosols are the byproduct of steam distilled plant material when making essential oils and less concentrated. Just make sure you are using a diffuser that uses water. Hydrosols can be expensive too. To make them last longer, you will want to use half water and half hydrosol. If you have a lot of hydrosols and their shelf life is coming to an end, you can use more hydrosols and less water in different variations. If you prefer, you can use only hydrosols in the diffuser.  My preference is to do 50% water/50% hydrosols. You will be pleasantly surprised at how aromatic it is without the possibility of irritation of the mucus membranes. If you are a person who is sensitive to smells, do 75% water/25% hydrosols.
What is the industry standard on drops/dosage?
The number of drops in a diffuser is really based on preference within the suggested
guidelines, the size of the diffuser, the size of the room, and the essential oils you are using. Your diffuser should have its own set of suggestions based on how much water it holds. The general guidance I have seen from one of my aromatherapy schools ranges from 5 drops to 15 drops.  Best practices for diffusing essential oils is 15 mins on 15 mins off, or 30 mins on 30 mins to a few hours off. There are some diffusers out there that have this feature to regulate the diffusion
times in intervals.
Education is key! Since I do not want to recreate the wheel, I am attaching a link in the references below of a Diffusion Class presented by Jade Shutes from The School of Aromatic Studies. This is a GREAT class, and it is free! She goes over the multiple diffuser options, their differences, how to clean them, and the recommended drops and diffusing time of each diffuser. She also attaches some handouts at the bottom of her video class, including an e-book with recipes.
If you have been diffusing for a while, you know common sense comes into play. If you are new to diffusing and essential oils, these are guidelines to start you on safe diffusing. This information may be new to many beginners and non-beginners since diffusing (indirect inhalation) is not typically discussed in this way. I have seen many people deny this information or not wanting to believe it because they have been diffusing for years, and everyone they know is okay with no issues. I have even seen a few aromatherapists argue amongst each other on this topic. That is fine, why? Because at the end of the day, it is your choice on how you wish to diffuse. I am just going to deliver the information so you are aware of what is being said out there. It is up to you how you choose to use the information I am providing.
Thank you for reading!
Love and Nature,
Remember: The contents of this blog post are intended for educational and informational purposes only and may not be the best fit for you and your personal situation. It shall not be construed as medical advice. The information and education provided here is not intended or implied to supplement or replace professional medical treatment, advice, and/or diagnosis. Always check with your own physician or medical professional before trying or implementing any information read here. Click here to read more about my medical/FDA disclaimers.
 Buckle, J. (2015). Clinical Aromatherapy, Essential Oils in Healthcare. Elsevier
 Michigan. (2002). Your Child’s Environmental Health How the Body Works: Differences Between Adults and Children [PDF]. https://www.michigan.gov/documents/ATSDRChildrensHealthhandoutsFS_155917_7.pdf
 Moms Clean Air Force. (n.d). Baby Power, Protect Little Lungs [PDF]. https://www.momscleanairforce.org/wp-content/uploads/2018/02/littlelungs.pdf
 Moya, J., Bearer, C. F., and Etzel, R. A. (2004). Children’s Behavior and Physiology and How It Affects Exposure to Environmental Contaminants. Pediatrics. 113 (Supplement 3) 996-1006. https://pediatrics.aappublications.org/content/113/Supplement_3/996
 United States Environmental Protection Agency. (2011). Exposure Factors Handbook Ch 6. [PDF]. https://ofmpub.epa.gov/eims/eimscomm.getfile?p_download_id=526167
 Carroquino,M., Posada, M., and Landrigan, P. J. (2012). Environmental Toxicology: Children at Risk. Environmental Toxicology. 239–291. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7121289/#CR6
 Butje, A. (n.d.). Aromatherapy Certification Program. [Courses]. Aromahead Institute. https://courses.aromahead.com/aromatherapy-certification-program
 Tisserand Institute. (n.d). How to Use Essential Oils Safely. https://tisserandinstitute.org/safety-guidelines/
 Shutes, J. (n.d). Diffusing Essential Oils. [Courses]. The School for Aromatic Studies. https://courses.aromaticstudies.com/product/diffusing-essential-oils-everything-youve-ever-wanted-to-know-online/