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How I Rate Fragrances
This guide covers how I rate home fragrances for their impact on your health. It explains what all the little symbols mean under the bathroom air fresheners and candles listed in the Healthy Design Shop.
You can use it as a guide when searching for home fragrance anywhere— the same information applies wherever you go.
Read more about why I rate fragrances and materials here.
Home fragrances— like candles, incense, and diffused aromatherapy— should be assessed for their potential impact on your health in three separate ways: what the scent itself is made from, what it is blended with, and how it is dispersed into the air in your home. This three-part consideration captures a more complete picture: for example, a perfectly healthy 100% organic essential oil may be blended with a petroleum-based wax and burned, releasing a slew of unhealthy chemicals into your home. On the other hand, a less-than-perfect oil may be safely diffused in pure water, making the second option a far healthier choice overall.
To stay organized and unbiased, I use the Standard Rating Scale to rate fragrance from healthiest to least healthy. Here’s a quick reminder about what each level on the scale means:
Healthiest option available.
Healthy, but doesn’t meet the strict standards of the blue dot.
Minimal health risk. Verified to be healthier than its standard counterpart.
Caution is warranted.
Well-known harmful effect on health and should be avoided whenever possible.
Here are the fragrance-specific requirements for meeting each level on the scale. Read on below for more details about terminology and specific examples.
Click on bolded statements to see links to research.
Third Party Certifications
What are 3rd party certifications? Why do they matter so much?
Third-party certification means that an independent group that didn’t make the product, and has no financial ties to the product, has reviewed, tested, and verified the claims that the company making the product has made.
Third party certifications protect you. Just like greenwashing makes products appear better for the Earth than they really are, some companies intentionally make their products seem healthier for people than they really are, too.
What is IFRA certification? Why is it rated so low?
The International Fragrance Association (IFRA) created its own Research Institute for Fragrance Materials (RIFM). This sounds good, but it’s entirely self-regulating. Its operations are opaque— they decide what chemicals are “safe” for use in fragrance (rather than requiring disclosure of ingredients, so consumers can make their own informed choice about whether its healthy enough for them or not.)
Many of the IFRA-approved ingredients, like benzophenone, methyleugenol and styrene, are known carcinogens.
When a company claims its scents are safe because they are IFRA-approved, it’s just not true. However, because they do limit some of the most harmful chemicals, I still consider IFRA-certified fragrance slightly better than uncertified fragrance.
Scent
Why are non-organic essential oils less healthy than organic ones?
Non-organic plants are typically grown with pesticides and synthetic fertilizers. These chemicals can remain in the final product.
Are natural fragrances healthy?
No.
Natural fragrance, aroma, parfum, luxury scenting, fragrance oil— these are all innocent-sounding words for the same thing: they’re synthetic fragrances, made from chemicals, in a lab.
The word “natural” isn’t defined or regulated in personal care products and fragrance in the United States, so it can be mis-used to make the product seem healthier than it is.
Unless a fragrance’s ingredients are “100% essential oil,” it is not truly natural.
How do I know if a fragrance is synthetic?
Unless it is labeled “100% essential oil,” it is probably synthetic.
Natural fragrance, aroma, parfum, luxury scenting, fragrance oil— these are all innocent-sounding words for the same thing: they’re synthetic fragrances, made from chemicals, in a lab.
Why are synthetic fragrances toxic?
Synthetic fragrances are notoriously bad for your health. They are associated with reproductive harm, asthma, heart disease, neurotoxicity, and more. There are 3,600+ synthetic fragrance chemicals currently, and dozens can be combined into one candle. These chemicals are often phthalates, which are endocrine disruptors.
Substrate
What does substrate mean?
The definition of a substrate is, “an underlying surface or layer.” For home fragrance, this is whatever the scent is mixed with or attached to, or what the scent travels along for release into the room. For this Rating System, I consider the following as “substrates”:
➜ Candle wax and wick
➜ Incense stick (typically bamboo coated in adhesive)
➜ Water
➜ Resin
➜ Biomaterials: Palo Santo stick, sage leaf, or pinecone
What is an example of a scent that would be in plain water?
Reed diffusers, electric evaporative diffusers, and regular spray bottles (non-pressurized) are all examples of delivery methods that rely on mixing a scent with water and releasing it into the room.
What are plant-based substrates?
Examples of substrates that are100% plant-based include:
➜ Hemp or cotton candle wicks
➜ 100% coconut or soy candle wax
➜ Biomaterials: Palo Santo stick, sage leaf, or pinecone
This differentiates from substrates that are not plant-based, like regular candle wax, which is made of paraffin (which comes from petroleum), or the glues used to adhere scent to incense sticks.
What is petroleum-based wax?
Usually called paraffin, standard candles are made with this. It is extracted from petroleum as a part of the oil refining process, mixed with solvents, distilled, and then further processed — making it softer or harder, or adding dyes to make it colorful. Burning petroleum, solvents, chemical additives, and dyes pollutes your indoor air and is associated with many health problems.
Some candles are labeled “coconut wax blend” or “soy wax blend.” When you see the word “blend,” it is likely blended with paraffin.
Why are incense sticks the least healthy option?
Incense, despite its association with spirituality and health, is surprisingly toxic when it burns. So much so that research groups have spent time and effort quantifying exactly what chemicals, and in what amount, are released upon burning incense sticks.
Most incense sticks are proprietary, meaning they won’t disclose what the exact ingredients are. Typically, they are made of a combination of the following: 21% (by weight) of herbal and wood powder, 35% of fragrance material, 11% of adhesive powder, and 33% of bamboo stick.
When they burn, they release 4 times the amount of Particulate Matter as a cigarette, several poisonous gases (carbon monoxide, nitrogen dioxide, and sulfur dioxide), polylcyclic aromatic hydrocarbons (PAH’s), formaldehyde, and phthalates. Wow! If you must burn incense, I recommend using ones that have 100% ingredient disclosure— and use sparingly in a well-ventilated room.
Throw Method
What is evaporation or manual diffusion?
For the purpose of this guide, evaporation and manual diffusion are the two ways in which scent moves into the air with the least manipulation, and the least change in its properties.
Liquid scent is naturally drawn into the air by evaporation over time, much like a puddle evaporates on a sunny day. This happens with reed diffusers, or after using a regular spray bottle (not pressurized aerosol) to spritz a scent into the air.
Electronic evaporative diffusers promote the same process, just faster. Think of using a small fan to encourage the scent to evaporate into the air.
What is nebulized or ultrasonic diffusion?
These are common diffuser types that have the potential to change the molecular size of the scent. Some claim to make scents “nanoparticles,” and while I can’t verify that’s truly what happens, I view them with some caution. Nanochemicals are so small, they can cross through our cell walls and even through our blood-brain barrier. The technology as a whole is very new, so while this may turn out to be a safe delivery method for scent, I still think regular evaporative diffusers are healthier options until we know more.
What are aerosols?
Think about spray paint, or a Febreze air freshener spray, when you think about what aerosols are. An aerosol is technically a suspension of particles in air, and requires a fancy can with a compressed gas to propel it out of the can into a very fine mist.
Aerosol scents are typically room fresheners. A variation of these is plug-in air fresheners — these use a tiny electrical circuit instead of your finger to “press the button” and release scented aerosol.
(FYI, regular spray bottles are not aerosols.)
What are propellants?
Propellants are compressed gasses in aerosol cans that force the scent out in its powerful, misty form. In the “olden days,” this gas was CFCs, or chlorofluorocarbons. However, CFC’s were banned because they were contributing to a big hole in the ozone layer. Now, other gasses are used instead. These are released along with the scent, so it’s important to use safe ones.
What is the difference between nitrogen and other gas propellants?
Harmful gasses are still used as the propellant in aerosol scent sprays. Benzene, a well-known human carcinogen, of which there is no level of safe exposure to, was found in many personal care aerosol sprays in 2021, forcing a major recall of those items. Ethanol may be a propellant that contains trace amounts of benzene (a carcinogen).
Some home fragrance aerosols use acetone and propane as propellants.
Nitrogen gas is currently considered the safest gas propellant. It is generally considered non-toxic and safe as part of an aerosol can.
So, avoid aerosols as scent delivery systems whenever you can. If you read the Safety Data Sheet and it specifically shows Nitrogen is the propellant, it is less dangerous than other options.
Why is combustion (burning a candle or incense) bad for you?
Combustion — AKA, burning candles, incense, palo santo, sage, etcetera — exposes you to smoke over minutes to hours, and is filled with fine particulate matter (PM 2.5), carbon monoxide, nitrogen dioxide, sulfur dioxide. Depending on whether or not the scent you’re burning is organic or synthetic, it also releases other gasses, VOCs, and phthalates into the air.
PM 2.5 is related to heart and lung disease, cancer, and is increasingly associated with developing dementia. It is the primary reason wildfire smoke and outdoor air quality warnings are issued, and is best kept to a minimum inside your house.
If you do decide to burn scents indoors, ensure they’re 100% organic and plant based, ventilate well, and I recommend use for special occasions only.
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