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Modern-day life is full of challenges, from little things like what groceries to buy to major issues like pollution slowly poisoning us in our own homes. No big deal, right? 

Well, seeing as over 34 million Americans suffer from respiratory problems like asthma, it’s a pretty big deal. Airborne triggers such as allergens, bacteria, and viruses pose a very serious threat to our health and well-being in this day and age.

Investing in an air purifier or dehumidifier (or both) might be a necessity for those who are conscious about their health and well-being. But knowing which appliance is best for your needs isn’t always straightforward. 

The key differences between an air purifier and a dehumidifier 

They might look the same, but don’t be fooled. They have completely different uses. Here’s a breakdown of their main differences:

1. An air purifier removes particles from the air

You can’t see it, but the air around you is full of pollutants and particulates that you inhale, which can ultimately affect your health. 

What type of pollutants are floating around your home, you may ask. They can range from everyday pollutants such as household dust or traffic pollution to volatile organic compounds (VOCs) like formaldehyde emitted from your furniture and carpets.

To keep these pollutants at bay, you can use an air purifier that draws in air and captures unwanted particles as they pass through a series of filters. That then leaves clean, healthy air that gets recirculated around your home. 

Air purifiers come with various types of filters. However, the vast majority use mechanical filters like HEPA and activated carbon, which are highly effective at reducing allergens and smoke and are even recommended for use against viruses such as COVID-19.

2. A dehumidifier removes excess moisture from the air

While a purifier removes pollutants, a dehumidifier removes water molecules from the air. 

The process starts in a somewhat similar way, as the humidifier also draws in air. But that’s where the similarities end. The next stage of the process depends on what type of dehumidifier you own: either a refrigerative or desiccant dehumidifier. 

• Refrigerative dehumidifiers cool humid air to create condensation (think of hot breath on a cold window pane). The condensation then collects in the unit’s internal reservoir as the dry air is warmed back up to room temperature and redistributed around your space. 

• Desiccant dehumidifiers pass humid air through a revolving desiccant wheel, which acts like a sponge to draw moisture from the air. Heaters then warm the dry air, ready to be expelled into the space, as well as heating the desiccant material to maintain its moisture-absorbing properties. 

Dehumidifiers don’t have filters, so they can’t remove airborne pollutants like an air purifier can. What they can do is create an environment that certain pollutants struggle to survive in. Many larger compressor dehumidifiers will include a filter, but this is designed to protect the internal coils from dust particles, not to clean your room’s air. 

By regulating humidity in your home you can reduce exposure to many common allergies, prevent mold and mildew growth, and create an inhospitable environment for pests like cockroaches and dust mites.

When to choose an air purifier over a dehumidifier

Both air purifiers and dehumidifiers can be a pretty sizable investment. Therefore, it’s important to know exactly when to buy an air purifier or a dehumidifier. You don’t want to spend all that money just for nothing to happen.

If you’re looking for protection from a wide range of indoor air pollutants, then an air purifier is what you need. These units can target the smallest airborne particulates as well as VOCs, creating a healthier environment within your home.

When to choose a dehumidifier over an air purifier

You might live in a humid region and desperately need dehumidifying to combat damp and mold. Then, an air purifier probably isn’t the priority.

For homes with damp or excessive moisture, a dehumidifier is the ideal choice. By controlling humidity in your home, you can expect to resolve issues with mold and mildew while creating an environment less susceptible to dust mites, invaders, and even bacteria. 

To conclude

Air purifiers and dehumidifiers may look similar, but they serve completely different purposes.

They’ll both improve the overall indoor quality of your home, but each space has different challenges that you’ll need to consider before investing in these appliances.

A dehumidifier is the logical solution for homes that struggle with excess humidity. It controls moisture levels, creating a healthier environment where mold, mildew, and dust will be less problematic.

On the other hand, air purifiers are ideal if you’re affected by a wide range of pollutants. By removing the problematic particles from your air, you can breathe easier in the knowledge your home is free from microscopic allergens and toxins that can contribute to an array of health issues. 

In a perfect world, you’d have both. When you have both appliances, you can get rid of pollutants and excess moisture. Double whammy. You can check out our recommended air purifiers and dehumidifiers if you want thorough analysis and real in-hand reviews.

When you walk into a room that smells like fruit or flowers, there’s probably a diffuser humming somewhere. 

Diffusers are a great tool to safely disperse essential oils, which can burn your skin if directly applied. Humidifiers, on the other hand, add moisture to the air, which acts as a temporary remedy for dry skin and congestion. 

Though similar in mechanics, their purposes differ; understanding these differences is essential before purchasing one or the other. What’s the fuss about these two products, and what makes them useful and different from each other?

This handy table breaks the basics down: 

From these differences, it’s easy to see that a humidifier is your friend if you need additional moisture. However, to make the air smell nicer, go for a diffuser. 

If you’re unsure if a product is a humidifier or a diffuser, check its tank size. Humidifiers often have large tanks holding about a gallon, while diffusers have a capacity equal only to about a cup of water.

Read on for more detailed ins and outs of diffusers and humidifiers. 

What is a humidifier?

Humidifiers rely on water to increase the moisture level in a room and can typically hold around half a gallon of water. Humidifiers aren’t usually necessary in wet or humid climates; a dehumidifier is your best bet. If too much moisture is in the air, mold can form around the house.

There are three main types of humidifiers:

• Evaporative humidifiers use a reservoir that stores cold water and empties it into a basin. A wicking filter absorbs water from the basin. It then blasts air through the wet filter with a fan.
• Ultrasonic humidifiers generate water droplets by vibrating a metal diaphragm at an ultrasonic frequency. 
• Steam humidifiers heat water and distribute it into the room as warm steam. This is the most basic and hence least expensive way of introducing moisture to the air.

The benefits of a humidifier

Humid weather doesn’t appeal to anybody, given that awful hot and sticky feeling. You likely already understand the frustration of having dry skin and a scratchy throat. Adding water to the air via a humidifier will help improve your skin’s hydration and can even unclog your stuffy nose. 

Additionally, more water in the air allows for easy breathing and helps prevent itching in your nose and throat. Breathing in dry air puts you at risk for a sore throat, sinus problems, dry cough and itchy nose. Increasing moisture in the air reduces these risks and soothes irritation in your airways. 

For productive coughs, humidity can also help your body clear mucus for more comfortable breathing. People with sinus problems will significantly benefit from these humidifiers designed to play nicely with their noses.

If you’ve bought a portable humidifier, you can hydrate one room at a time. The time it takes to raise the humidity levels in a room depends on your humidifier’s size and the volume of the room. 

Humidifiers are most commonly used in winter when the air is dehydrated. You can buy both “cool mist” and “warm mist” varieties, letting you adhere to your desired room temperature while protecting your skin and keeping you fresh and comfortable.

What is a diffuser?

Diffusers are a safe way to disperse essential oils around your home. Oils evoke different feelings and moods and improve your mental and physical state. This art of choosing scents is called aromatherapy.

Not all diffusers are designed the same. There are four common types: 

• Evaporative diffusers are fitted with little fans that blow air through a piece of tissue or pad holding drops of essential oil. The air that comes out of the machine is beautifully scented.
• Heated diffusers work by evaporating water and essential oils into the air. Typically, you drop your oil into the water, and the solution is heated gently. The resulting vapor is then released into the air. 
• Ultrasonic diffusers don’t use heat; they use high-pitched sound frequencies that produce vibrations, jostling the essential oil particles and releasing them as mist.
• Nebulizer diffusers are recognized by their “droplet” shape that tapers into a thin nozzle at the top. Pressurized air breaks down essential oils into particles and shoots them as a mist. Uniquely, no heat or water is required. 

The benefits of a diffuser

Diffusers are useful tools for aromatherapy. Breathing in certain smells can alter your mood, making you feel refreshed or relaxed. You can use your diffuser during meditation or a massage for added serenity. 

Another upside is that diffusers are also easy to use. You may need to add water or insert a cotton pad with drops of essential oil, but that’s just about it. 

Some diffusers also come with blinking lights, but if this interrupts your sleep, buy one that allows you to control this feature. Additionally, most diffusers operate quietly, so getting a good night’s sleep is a lot easier.

Once you’ve got the hang of aromatherapy, feel free to try out any essential oil you like. Citrus, rose, tea tree, sandalwood and peppermint are great options for starting out.

What about humidifier and diffuser combos?

Using one for the other is not recommended if you have an older humidifier or diffuser. That is, you generally shouldn’t use a humidifier as a diffuser (or vice versa). Essential oils can damage your humidifier and diffusers simply don’t hold enough water to be effective at moistening the air. You should have a separate diffuser for your aromatherapy needs.

Understandably, buying two devices can be costly or appear unsightly. Fortunately, it’s now possible to buy humidifiers that double as diffusers.

If you’re a fan of a two-in-one, Honeywell has a range of warm mist and ultrasonic cool mist humidifiers specially designed to hold essential oils. This way, you gain access to the benefits of moist air while also having the option to add some fragrance depending on your mood.

For a compact humidifier + diffuser combo that fits perfectly on your work desk, check out Honeywell’s Ultra Glow Light Changing Humidifier and Diffuser. It even has a neat adjustable light feature that’s perfect anywhere in the house, any time of the day. 

Final thoughts

Despite being different products, humidifiers and diffusers create a cozy, soothing home atmosphere that helps improve your mental and physical well-being.

The added moisture in the air treats dehydrated skin and relieves an itchy, congested nose and throat. With a diffuser, you can set the mood for a relaxing night or a meaningful meditation session. These two products will refresh you and are just the pick-me-ups you need in your home. 

And with modern technologies, you can even combine them into one product. With this duo combo, a house truly becomes a home.

It’s widely known that the air inside our homes contains pollutants of all sorts. From dust, pollen, pet dander, and mold spores (all allergy triggers) to viruses, bacteria, and volatile organic compounds (VOCs). The greater our understanding of indoor air pollution, the more popular air purifiers become. 

These appliances are an effective solution to deal with pesky contaminants, especially when ventilation proves insufficient or when unable to remove the source of pollutants, like when living next to a busy road. 

On top of all that, there are so many devices and technologies on the market that make things super confusing.

Purely mechanical air purifiers (HEPA and activated carbon filters) and electronic air cleaners (ionizers) have the same function: they remove airborne pollutants. But their mechanisms differ greatly — and so do their cleaning capabilities.

In a nutshell:

•  Mechanical air purifiers use a fan to pull in air, pass it through the HEPA and activated carbon filters that trap the pollutants, and release a clean airflow into your space.

• Ionizers release an electrostatic discharge into the air that alters the particles’ structure, which forces them to drop out of the air.

The key differences between an air purifier and an ionizer

While both types of air cleaners may look similar from the outside, their mechanisms are nothing alike. Let’s find out why.

1. Air purifiers trap airborne pollutants through filtration and adsorption

As briefly explained above, mechanical purifiers pull the air from the environment and pass it through their filters before releasing clean air. Filters are made of different fibrous media, meaning they can trap pollutants on their surface.

As shown in the illustration, most mechanical air purifiers have a three-stage filtration process: a pre-filter, an activated carbon filter, and a HEPA (or HEPA-type) filter. Each stage tackles different types and sizes of contaminants. 

Pre-filter: The first layer of protection. It prevents large particles (such as lint, coarse dust, or hair) from getting to the main filter. Prefilters need regular cleaning and upkeep to maintain efficiency.

Activated carbon: This layer tackles pollutants in their gas form. The carbon adsorbs odors, VOCs, and other toxic fumes, which get trapped on the porous surface of the charcoal, making them unable to reenter the air. 

HEPA (high-efficiency particulate air) filter: This main filter is made of randomly assorted fine fibers in the form of pleated sheets. It’s constructed like a maze to capture even the tiniest particles (as small as 0.1 microns) like smoke. When the airflow passes through the filter, over 99% of fine particles get tangled in the fibers, accumulating on the filter’s surface. 

2. Ionizers induce particle deposition but don’t trap pollutants.

Although ionizers do remove particles from the airstream, they don’t collect them.

As the name suggests, ion generators use imperceptible electrical discharges to release ions into the air. Some devices produce only negative ions and are known as unipolar ionizers. Bipolar ionizers, on the other hand, produce and release both positive and negative ions. Despite this difference, they use the same principle: electrically charging pollutants to force them to drop from the airstream. 

The ions become airborne in air or water vapor molecules, which are then attracted to oppositely charged pollutants, such as bacteria, mold spores, and other small to mid-sized particles that inhabit our indoor air. These clusters of ions, attached to pollutants, become heavier and fall down, depositing on oppositely charged surfaces around us: furnishings, curtains, beds, couches, tabletops, walls, or floors. 

Once the clusters land on these surfaces, they’ll stay there for some time, which you can vacuum or sweep. In fact, when using an ionizer, you’ll probably see more dust deposits around. Be mindful, however, that you’ll have to remove them periodically before the clusters break apart and the particles become airborne again.

3. Ionizers produce potentially dangerous by-products. HEPA and activated carbon are harmless

One huge downside of ionizers is that they generate harmful by-products. The electrical discharges and artificial introduction of ions into the environment produce multiple chemical reactions besides particle deposition. They can alter molecules in our homes, turning them into toxic fumes such as ozone, acetone, ethanol, toluene, and aldehydes.

CARB has tested many ionizers, and the agency found them to produce ozone concentrations as low as 0.05 parts per million (the maximum ozone level set by the FDA). However, the EPA states that, even at those levels, ozone can react with common household chemicals. Fumes from cleaning products, polishes, and wood flooring, among others, can react with ozone and produce further VOCs.

But that’s not all. Ozone can also react with compounds such as terpene, found in air fresheners, and create ultrafine particles, adding secondary harmful aerosols instead of removing them. 

Now, when it comes to mechanical air purifiers, both HEPA filters and activated carbon are harmless — they produce zero by-products. These devices operate with one goal in mind: to remove pollutants from your environment.

4. Research backs HEPA filters, but the verdict is still out there for ionizers.

HEPA filters were developed during World War II to control the spread of radioactive pollutants and remove them from the air. Since then, they’ve evolved into the commercial filters we now know, used in an array of air cleaners. Their filtering mechanism, however, remains pretty much the same. 

Performance-wise, filters must meet strict quality standards. In the U.S., a HEPA filter has to be capable of removing at least 99.97% of pollutants as small as 0.3 microns. Meanwhile, the scientific literature suggests that they have multiple health benefits, such as:

• Enhancing overall respiratory health and lung function
• Reducing allergy and asthma symptoms
• Improving cardiovascular health by decreasing blood pressure and oxidative stress

In contrast, academic research on ionizers is controversial, to say the least. For quite some time, there was a lot of hype about negative ions’ positive physical and mental health benefits. They became even more popular after claiming to kill viruses such as COVID. And yet, when you dig just a little deeper, most papers conclude that these claims don’t hold up.

But it’s not only dishonest advertising we should worry about. Besides the risks of ionizers’ by-products, the EPA warns about the dangers of particle deposition. The rates of fine particle deposition in the lungs and respiratory tract are higher for charged particles than uncharged ones. According to CARB, fine particulate matter, such as PM2.5, is considered to cause the most health issues associated with air pollution.

In line with this article by Colorado State University, as long as the industry sets parameters for testing standards and blocks peer-reviewed research, paid-for reviews on ionizers will continue to be commonplace.

The pros and cons of air purifiers

When it comes to mechanical air purifiers, it’s easy to pinpoint the advantages, although it’s harder to identify drawbacks.

Still wondering if you should get an air purifier? This infographic could have the answer you are looking for.

The pros and cons of ionizers

Identifying the strengths of ionizers is not as easy, to be honest. There are some perks and benefits, for sure. But there are far more cons.

A case for air purifiers with an on/off ionizer function

You may have come across air purifiers with built-in ionizers. We’ve tested several of these units here at HouseFresh, such as the Winix 5500-2, the Coway Airmega AP-1512HH Mighty, and the Alen BreatheSmart 45i/75i, to name a few. Unlike Blueair units, these units come with a handy on/off button for the ionizer. 

These devices combine technologies to offer an alternative to traditional unipolar and bipolar ion generators. For starters, true HEPA filters can remove fine particles, such as those produced by ionization reactions. At the same time, electrostatically charged particles are stickier than uncharged ones, which makes them adhere to the HEPA fibrous media, enhancing the filter’s efficiency.

Additionally, activated carbon filters can adsorb ozone emissions, sometimes before it even leaves the unit  (if the output is low). If the filter is robust enough, which is the case with Winix and Alens units, it can also adsorb other VOCs produced by the ionization reaction. 

However, neither unipolar nor bipolar ionization is something to take lightly. Despite genuine and trustworthy certifications, such as those carried out by CARB or other approved entities, most experiments are conducted in laboratory chambers. These tests cannot emulate accurate real-world conditions nor guarantee that an air cleaner will produce zero by-products.

That’s why we’re supporters of air purifiers with an ionizer function that can be disabled, so you can choose when to activate it, if at all. If you’re ever unsure or feel uncomfortable with the ionizer on, you can simply switch it off and still enjoy the benefits of a mechanical air purifier.

Wrapping up

Throughout the article, we’ve explored the risks and (partial) benefits of ionization. In truth, ionizers alone fall short of expectations. 

I’d think twice before investing in an ion generator. But I will say, air purifiers with an optional ionizer function are a different story. Hybrid air cleaners can be more efficient. And I prefer choosing when to boost the purifier’s performance with the ionizer.

On the other hand, mechanical air purifiers are both reliable and safe devices for improving indoor air. They are, without a doubt, my go-to choice.

Often, air purifiers and humidifiers are lumped together in the same category. It can be confusing which one you need for your home. Granted, they can both improve your indoor air quality, but that’s where the similarities end.

You’re probably asking yourself, “What’s the difference?” and maybe more importantly, “Which one do I need?” 

In this post, I’ll take you through the key differences between air purifiers and humidifiers, what they do, how they do it, and which device would suit your situation best.

Key differences between air purifiers and humidifiers

Before we go any further, I want to address the major difference between an air purifier and a humidifier as simply as possible.

Air purifiers clean the air, humidifiers add moisture to the air.

It may sound simple, but what exactly does that mean? Let’s examine each product closely to establish the key differences.

1. Air purifiers clean the air in your home

According to the EPA, the average American spends around 90% of their time indoors, where the air is full of pollutants. If not removed, these pollutants can have adverse immediate and long-term effects on our health.

Air purifiers pull air into the unit using a fan, pass it through a series of filters, and then push the clean air out. The filters trap microscopic pollutant particles (allergens, odors, dust, VOCs, etc.), leaving you with clean air.

There are thousands of air purifiers on the market. Some great and some not. So, it’s worth doing a little research before choosing the right one for your home. Check out our guide: What size air purifier do I need? to help with your journey.

2. Humidifiers add moisture to the air

Low humidity can be an issue in your home, especially in the winter months. It’s not only uncomfortable to live in, but it can cause dry skin, eye irritation, and also make it hard to breathe. Studies have shown that introducing a humidifier into your room can relieve respiratory symptoms, alleviate dry skin, and even decrease the survival of influenza viruses.

Humidifiers draw in air from your room, introducing it to moisture from a water tank through a wick or mixing it with steam. The wet air is then released into the environment, mixing in with your air.

There are three main types of humidifier:

• Evaporative humidifier – This unit has a reservoir that stores cold water and empties it into a basin. The water is absorbed from the water using a wicking filter. It then blasts air through the wet filter with the help of a fan.

• Ultrasonic humidifier – This type of humidifier generates water droplets using a metal diaphragm. This component vibrates at an ultrasonic frequency (similar to a high-frequency speaker). An ultrasonic humidifier is usually quiet to run and creates a cool fog.
  
  
• Vaporizer humidifier – AKA a vaporizer, heats water and distributes it into the room as warm steam. This is the most basic and least expensive way of introducing moisture to the air.

When to choose an air purifier over a humidifier

Air purifiers can be costly investments, so understanding when to buy one over a humidifier will save you a lot of frustration and money.

When to choose a humidifier over an air purifier

Humidifiers can be a great addition to your room, allowing you to maintain a healthy humidity in the air. But, there are some things a humidifier cannot do.

To conclude

Even though they look similar and deal with air quality, air purifiers and humidifiers have very different roles in your household. Remember the golden rule: air purifiers clean the air, humidifiers add moisture.

The good thing is you can run both in the same room simultaneously. You can have clean and moist air as they perform different tasks.

There is a third alternative. Brands have started combining air purifiers and humidifiers in the same unit. But I always air on the side of caution when I see combo units. If a device tries to do two jobs, it probably doesn’t do either to an acceptable standard. 

Check out our review of the Dyson PH03 Air Purifier and Humidifier to see Danny’s verdict on one of the best-selling purifier/humidifier combos on the market.