How do Essential Oil
Diffusers Work?

Diffusers are incredible little devices. They can not only provide (usually) much needed humidity to your home or office, but also a multitude of therapeutic benefits through the diffusion of essential oils.

You may be curious however, a diffuser works! In this article we’ll outline how the four different types of diffusers work (ultrasonic, nebulizing, heat and evaporative) which also may help you choose between the two if you happen to be debating. Let's dive in and answer this burning question: how does a diffuser work?

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diffuser on bedside table

Which Type of Diffuser is Best?

If you’re trying to decide between the two types we recommend: an ultrasonic or nebulizing diffuser, it can be a tough choice since they both have their own unique set of benefits and drawbacks.

Nebulizing diffusers typically produce better therapeutic effects, since they release essential oils directly into the environment and is not diluted through water vapour. However, they are a little more expensive typically, and don’t humidify the air.

Ultrasonic diffusers are typically more affordable, however are slightly less effective than nebulizers since the oils are carried through water vapour droplets and subsequently diluted. However, they can provide therapeutic effects and also humidify your space simultaneously.

Heat diffusers are affordable, but dangerous due to the open flame.

Evaporative diffusers can be low maintenance, but don't have the same performance as a nebulizer or ultrasonic. 

To learn more about the types of diffusers and to help you decide, check out our list of the best essential oil diffusers. 

Now, let's go over the four types of aromatherapy diffusers and how they work. 

How an Ultrasonic Diffuser Works

Ultrasonic diffusers disperse their essential oils into the air by being carried in tiny micro-droplets of water vapour.

The water is converted from liquid into water vapour using ultrasonic vibrations. These ultrasonic vibrations are actually produced by a vibrating disc that produces sound waves at an ultrasonic frequency which we can’t actually hear.

The waves churn the water within the reservoir of the diffuser – which also contains the essential oils – at such a high rate, it actually converts the water to vapour, or mist, which then disperses throughout your room.

The ultrasonic waves also disrupt the oil bubbles within the water and trap them inside the water droplets, which is how the smell and therapeutic effects of the oils are carried throughout your space.  

How a Nebulizing Diffuser Works

A nebulizing diffuser works a little bit differently from an ultrasonic diffuser. The main difference is that a nebulizing diffuser does not require a water reservoir, nor do the essential oils being diffused do so through a carrier water droplet.

Instead, these diffusers work through a scientific principle called Bernoulli’s Principle, a fluid dynamics theory of physics.

In nebulizing diffusers, air is shot through a small tube at a very high velocity, it also produces a difference in pressure within the tube – that is, the pressure near the exit of the tube is lower.

The pressure difference produces a suction-like effect causing the essential oils at the base of the tube to be sucked up towards the top of the tube.

The combination of the rising essential oils and the stream of pressurized air produces a similar effect to an ultrasonic diffuser – the essential oil molecules atomize into tiny particles in a waterless mist that disperses throughout your room.

How an Evaporative Diffuser Works

Evaporative diffusers typically come in two classes: passive and active.

Passive Evaporation:

A reed diffuser is a perfect example of a passive evaporative diffuser you may already be familiar with. Reeds are porous wooden materials and function like a wick in a lantern. 

Due to their porous nature, they are effective at capillary action, by which oil wicks up from the container they are in and up to the tip of the reed. Then, they evaporate into the air. 

a picture of a reed diffuser

There's no noise, no power required, no water to replace, but the scent isn't quite as powerful as an electric diffuser. 

Other examples of passive evaporative diffusers include essential oil necklaces or bracelets. 

Active Evaporation:

An active evaporative diffuser involves a small fan that blows across the surface of an absorbent pad, soaked in essential oils. This produces just the right amount of energy required for the oil molecules to evaporate out into the air. 

This is somewhat similar to both ultrasonic and nebulizing diffusers. Unlike ultrasonic diffusers, you don't need water, but you do need to replace the pad often. Like nebulizers, it only requires oil, but you don't get as much out of it. 

For these reasons, evaporative diffusers are not as popular as ultrasonic or nebulizing diffusers. 

How a Heat Diffuser Works

Heat diffusers are more like evaporative diffusers than their other relatives, since they also require on evaporation for their action, but instead of a fan that blows cool air, they use heat to speed up the process.

Heat diffusers are affordable, since you pretty much just need a single candle to do its job, but they lack a lot of features that electric diffusers do, including safety features.

There's no automatic shut off on a candle, it'll keep burning until the wax runs out. And, they're just more dangerous since you're using an open flame. 

And, heat can often fractionate the oils you're heating up to diffuse, providing impurities and bad smells. If you're spending money on high quality pure essential oils, you want to get the most out of them. 

Want to Know How to Select a Diffuser?

Now that you understand how the different types of diffusers work, it's time to get you your own! We've reviewed dozens of diffusers and know exactly what to look for. Check out our reviews to find the right one for you.