Do air purifiers really work? Expert review & 2026 buying guide

It is estimated that 99% of the world’s population breathes air that exceeds air quality standards. Air pollution is an often invisible problem but one that impacts many aspects of both human and environmental health. Indoor air quality is a subject of growing importance given that indoor air is 2 to 5 times more polluted than outdoor air. We cannot control outdoor air quality, but we do have the ability to clean the air of dangerous airborne particles indoors with high-performance, medical-grade air purifiers. How do air purifiers work? How do I know if I need an air purifier? Do air purifiers really help protect us from the dangers of indoor air pollution? Read on to learn more.

How do air purifiers work?

Filtration mechanics and health benefits

An air purifier is a portable device that uses an internal fan to pull in polluted air from a specific space, treats the air inside the device using various filtration technologies in order to remove unwanted particles, and then circulates the purified air back into the room. Depending upon the level of indoor air pollution of the space, air purifiers work by repeating this process several times an hour. The goal of an air purifier is to reduce our exposure to harmful indoor air pollution and protect our health and well-being. Some ways an air purifier can do this are by:

• Lowering the risk of air pollution-caused illness and disease
• Easing symptoms of allergies to pollen, dust, pet dander, or other allergens
• Reducing attacks and symptoms for those with asthma
• Protecting vulnerable populations like children and infants, pregnant women, elderly individuals, and the immunocompromised

It is worth noting that all air purifiers require regular filter changes. It is important to replace your filters in order for your device to continue to function properly. Devices with saturated filters can even increase your exposure to air pollutants by releasing them back into your air if filters are not maintained.

For which environments are they best suited?

These devices are intended for use in homes, in offices or other professional environments, in schools, and even in cars.

What can an air purifier filter out?

It is important to understand that not all air purifiers are created equal. This means that they do not all guarantee the same level of protection from exposure to air pollution. Filter type plays a major role when it comes to determining an air purifier’s efficiency.

HEPA filters:  capturing airborne particles

The most important thing to look for whilst researching your future air purifier is to ensure that it contains a filter that is HEPA-certified (also known as “true HEPA”). What is a HEPA filter, and why is it important in the fight against indoor air pollution?

‘HEPA’, or ‘high-efficiency particulate air’, is the gold standard of air filtration. HEPA is a European certification overseen by European standards EN 1822 and EN ISO 29463. These filters have been used for decades in laboratories, operating theatres, and cleanrooms. A proper HEPA filter can filter out bacteria, viruses, common household substances that cause respiratory allergies (such as pet dander and pollen), pollution like dust and smoke, mould spores, VOCs (volatile organic compounds that can be harmful to our health and well-being), and more1.

There are multiple HEPA grades ranging from H11 to H14 (the finest filter mesh). Both HEPA H13 and H14 filters are considered to be “medical-grade”. Medical-grade HEPA filters are capable of filtering, in a single pass, at least 99.97% of fine particles of a size greater than or equal to a diameter of 0.01 µm.

Activated carbon filtration and advanced technologies

A high-quality air purifier may also come equipped with other technologies such as an activated carbon filter. Thanks to its high gas absorption capacity, activated carbon is incredibly effective at fighting against chemical pollution and unpleasant odors. This is why activated carbon filters can be found in places ranging from storage boxes for cheese to vacuum cleaners. Carbon filters are an essential technology found in most air purifiers because they remove chemical pollution like volatile organic compounds (or VOCs), a capacity that HEPA filters do not have. Using both technologies in tandem is fairly universal in quality air filters.

Ionisation

Furthermore, some air purifiers function as an air purifier and ioniser simultaneously. Ionisation is a technique that is particularly recognized for its high efficiency against particulate pollution (fine particles, nanoparticles, and dust). Negative ions are highly reactive (due to their polarity). They attach themselves to pollution particles of positive polarity and will either disintegrate these positively-charged particles or will weigh them down and drop them to the ground, far away from your lungs.

Research studies on air purifier efficacity

The above information may be useful, but what does science say? Do air purifiers work in the way they are intended? Are they able to protect us from harmful air pollutant exposure and unpleasant allergy symptoms?

A 2020 study found that air purifiers ‘quickly reduced PM2.5 levels from 20.64 μg/m3 to 5.58  μg/m3’ when analysed in both a living room and a bedroom setting2. 

A 2021 study in various educational settings in Poland measured an air purifier’s ability to reduce airborne bacterial contamination. It reported a reduction of about 20% of bioaerosols and microbiological pollutants3.

Another 2021 study found that HEPA-certified air purifiers removed 29 to 53% of PM levels of different sizes in general indoor air4.

A 1997 study assessed the effectiveness of air purifiers over a period of six months, focusing mostly on particulate matter and allergen levels. Findings showed that HEPA-certified air purifiers were capable of filtering 70% of 0.3-μm particles and 95% of 1.0-μm particles, proving ‘the capacity to capture substantial amounts of airborne dust particles and airborne allergens’5.

A 2014 study on particulate matter levels in children’s bedrooms found that air purification devices removed, on average, 50% of PM concentrations6.

One additional study in 2012 published results showing that air purifiers reduce between 69 to 80% of particulate matter concentrations in homes, supporting their use especially in homes with asthmatic children7. People suffering from asthma benefit greatly from having an air purifier at home; these devices are particularly helpful in warding off asthma attacks.

Eoleaf devices were put to the test during the coronavirus pandemic by a third-party laboratory, Octopus Lab. Our devices were proven to reduce airborne viral contamination by 40% in environments without masks, and upwards of 90% in environments with masks. They were also tested and proven to be effective against particulate matter and substances that cause allergies. Refer to our article linked above for more details.

What to consider when buying an air purifier

Consider performance and the size of your space

In order for the air in your room or home to be properly cleaned and to protect your health and well-being, you must purchase an air purifier that is properly sized to suit your space. Each air purifier has a recommended room size for optimal performance. Once you have chosen the air purifier that best suits your needs, we recommend purchasing a model that is sized for a space slightly larger than the one in which you are looking to install the air purifier. This will ensure a thorough cleaning and purification of the air in your space.

A useful way of properly sizing your unit and determining your air purifier’s capacity and performance is by using two metrics: the “clean air delivery rate” (CADR) and “air changes per hour” (ACH).

CADR is used to measure an air purifier’s ability to purify pollutants from your indoor space. It enables you to know the volume of air that can be treated by the device, and, thus, the room size it can properly filter. CADR is either measured in m3/h in metric of CFM units in imperial.

ACH indicates the number of times that a room’s entire volume of air is renewed with purified air per hour. Using an ACH value of 5 (the minimum ACH value recommended by the Centre for Disease Control), this means that the air is replaced 5 times per hour. Calculate your ACH using the following simple equation:

• ACH = CADR / volume of room

To ensure that your air purifier is properly sized to your space, refer to our guide to air purifier sizing.

Consider your pollution type and type of filter

Which pollution type is of the most concern in your indoor space? Are you looking for a solution to combat mould and spores, fine particles, or chemical pollution like VOCs? Are you experiencing unpleasant allergies due to pollen, dust, or other allergens in your home? Maybe you have a neighbour who smokes, causing a nuisance to you in your space? Perhaps eliminating germs like bacteria and viruses from your space is your goal?

Most air purifiers contain one or two filtration technologies that are designed to combat certain types of pollution. A HEPA-certified filter, for example, is great for fighting against fine particle pollution like PM10 and PM2.5, as well as allergens like pollen or dust and cigarette smoke. Ionisation depolluting technologies are also excellent for fighting against fine particulate matter. However, neither of these technologies are able to remove VOCs from your breathing air. For this, you will need a device that is equipped with an activated carbon filter. Photocatalysis is another useful technology in removing VOCs from your indoor air.

If you are hoping to remove bacteria and viruses from your space, ultraviolet (UVC) sterilisation technology is your best bet.

A great way to ensure that your air purifier combats all types of pollution is to purchase one that does exactly that! Eoleaf devices use a proprietary 8-step filtration system that ensures all of the above types of pollution are removed from your indoor air.  

Consider the noise level and placement

When choosing your device, be sure to choose one that is powerful but quiet. A quiet air cleaner will not disturb your day-to-day life. Additional features like Night mode will also respect your sleep by reducing its fan speed to its lowest level and shutting off its indicator lights.

Remember: proper placement of your air purification device can dramatically improve its efficiency! Think about where you plan to install your device before you make your purchase. An air purifier works best when it is placed far from corners and walls, unimpeded by furniture or shelving. Be sure that its air inlets and outlets are unobstructed and that it is positioned in a place with optimal airflow.

Consider smart features

More modern, smart air purifiers with Wi-Fi connection can also serve as a very useful tool in helping you understand the quality of your indoor air. Your device can tell you the levels of air pollution in your space in real-time in addition to the air temperature and humidity levels in your space. Some devices provide air quality indicators by colour. Find Eoleaf’s air quality indicator colours below:

• Excellent: green

• Good: blue

• Poor: yellow

• Very poor: red

Furthermore, some devices come equipped with the convenience of an Automatic mode (auto mode). You will find this on all Eoleaf devices. This setting allows your air purifier to automatically adjust its fan speed depending upon the level of air pollution it detects. This feature provides consistently clean air and reduces your exposure to pollutants even when new pollutants are introduced into your space.

Certain devices on today’s market even have a smartphone app specifically designed for air purifiers. This is a greatly helpful tool, allowing you to gain more insight into your indoor air quality. You can even set smart scheduling to automate its functions. Eoleaf devices use the Tuya Smart app.

Additional features that you may find offered by high-quality air purifiers may include a Bluetooth remote control, a filter change indicator, wheels and/or handles for easy movement, a timer function, and Night mode. Find all of these features and more integrated into Eoleaf devices!

Consider budget and energy consumption

Air purifiers vary drastically in their options and, as a result, their price tag. There are three parts to consider when budgeting for an air cleaner: 1) the initial cost, 2) the maintenance costs, and 3) costs associated with energy consumption.

Learn more about how much an air purifier costs and how to budget for an air purifier by referring to our article here.

An efficient air purifier does not have to consume large quantities of energy. High-performance air purifiers, like those offered by Eoleaf, are both powerful and engineered for low energy consumption. Running an Eoleaf air purifier 24/7 costs just a few cents a day on your electric bill.

What are the best air purifiers in 2026?

 

Now that you know what to look for in a high-performance air purifier, how do Eoleaf models stack up against the competition? The table below provides an in-depth look at the industry’s forerunners of 2026. 

Note that the air purifier market does offer some, though few, 2-in-1 climate control air purifiers (dual air purifiers and air conditioners). These are units that provide heating and/or cooling as well as air purification. These units are few and far between: Dyson is one of the most well-known brands that markets these devices. It is highly recommended to be wary of these devices: air purifier filters are highly sensitive to drastic changes in temperature and humidity. Climate control within an air purifier may cause serious damage to an air purifier’s sensitive filter mesh, dramatically reducing its filtration capacity and reducing its lifespan

Are air purifiers effective for allergies, smoke, and viruses?

Allergies

Whether or not an air purifier tackles allergies is determined by the filtration technologies it contains. Allergy symptoms are typically caused by fine and nanoparticles present in your indoor breathing air. When inhaled, the body incorrectly identifies the particles as dangerous, causing an immune response (which manifests as the unpleasant symptoms we know as allergies like a runny nose, an itchy throat, and even asthma symptoms in more severe cases). Allergenic particles can sometimes be classified as nanoparticles, measuring as small as 0.01 microns. Removing allergens of all sizes including dust, dust mites, pollen, mold and mold spores, and pet hair and pet dander from your indoor air so that your respiratory system is significantly less likely to inhale them is an easy way to improve allergy symptoms - but only if the air purifier is HEPA certified! Without certification, its efficiency in removing even the smallest particles that trigger allergy symptoms cannot be guaranteed.

Smoke

Smoke contains not only fine and nanoparticles. It also contains chemical pollution (which includes VOCs, ozone, and carbon monoxide, to name a few). This applies to all types of smoke: wildfire, cigarette, cigar, cannabis, and even e-cigarettes. This is why it is so important to ensure that an air purifier contains a variety of high-quality air purification technologies that target all forms of indoor air pollution. The air purifier market is diverse, offering air purifiers with a wide variety of filter types and filtration technologies to tackle air pollutant particles of various sizes including pre-filters, HEPA-certified filters, activated carbon filters, ionisation, UV sterilisation, photocatalysis, and more. Eoleaf’s air purifiers, for example, boast all of the above as part of our 8 filtration technologies!

Viruses

Eoleaf air purifiers are highly efficient at the removal of all types of germs including bacteria and viruses. This is thanks to their medical-grade, HEPA H13-certified filters that guarantee the removal of 99.97% of all pollutants down to 0.01 microns but also due to their UVC sterilization technologies. UVC sterilization is an essential technology not only for its efficiency against airborne germs but also for its ability to protect the user from recontamination. When viruses and germs are removed from the air by a high-end air purifier, those germs do not simply disappear: they are safely stored inside the air purifier’s filter where they remain until the filter is replaced. This does mean, however, that there is significant risk of recontamination when the filter is accessed and handled during replacement. UVC sterilization makes the filter safe for handling by killing or deactivating the bacteria and viruses present within the filter

What are the top-rated air purifiers according to independent reviews?

When evaluating top-rated air purifiers, independent reviews are helpful in choosing the right model for your air purification needs. Publications like WireCutter, HouseFresh, and Consumer Analysis are all useful tools in highlighting certified performance claims. These publications typically use expert review methodologies that focus on some of the most valuable benchmarks in the industry like CADR, energy consumption, noise levels, and more.

However, these publications do have their limitations and do not tell the whole story. Mainstream testing tends to focus heavily on entry-level units like the Coway Mighty or the Winix Pro series. These units typically earn strong ratings for basic air purification (particulate removal in smaller rooms). These units often lack high-performance technologies that target all types of indoor air pollution, including more complex indoor air pollution and chemical pollution like VOCs.

This is where professional-grade air purifiers outshine entry-level units and standard consumer ratings. Medical-grade air purifiers, like those offered by Eoleaf, are equipped with eight third-party tested technologies that extend far beyond standard benchmarks and testing. Although conventional editorial reviews guide budget starting points, the only way to find genuine high-performance filtration systems is to perform independent research, confirm certifications, and ensure multi-technology coverage.

To see how Eoleaf customers experience the difference in air quality, read verified customer reviews here.

What are the common issues with air purifiers and reasons to avoid certain models?

When purchasing an air purifier, it is important to educate yourself beforehand on the multiple factors to consider, but it is also important to understand your own needs. Choosing the wrong unit can both harm your health and be a waste of money. The worst air purifiers are typically those that are designed to cut costs for the manufacturer. Refer to our list of reasons to avoid low-cost air purifiers and common issues found in sub-par units below:

• Dangerous ozone emissions: This is a common issue in low-cost air purifiers. Ensure that the device is certified ozone-free before purchasing. Eoleaf air purifiers all use needlepoint bipolar ionisation with a voltage charge of 5.0 kV. This technology has been utilized for twenty years and produces no ozone.

• Undersized CADR ratings: Low-quality air purifiers often list unrealistic room coverage. Verify the CADR rating of the unit before purchasing: an air purifier with a low CADR cannot circulate purified air throughout your space fast enough and will leave air untreated. An undersized unit will also work harder than it needs to, causing faster wear-and-tear.

• Noisy fans: Poorly engineered, cheap air purifiers will generate significant levels of noise, creating problems for those who are sensitive to noise. This generally forces the user to leave the device running on only its lowest fan speed, even when faced with new incoming pollutants that require a faster fan speed for removal. 

• Hidden filter replacement costs: This is a very common issue in the air purifier industry that is easy to avoid for the well-prepared. Low-cost air purifiers, although cheaper initially, are often equipped with lower quality filters that require filter replacements multiple times per year! Customers are also even required to purchase multiple filters. This ends up being an expensive long-term mistake. Eoleaf air purifiers are equipped with filters that are engineered to last an entire year. All 8 technologies are found within one convenient filter block, so there is no need to purchase multiple filters.

• Incomplete seals: Poorly designed, improperly sealed air purifiers allow air to bypass the filter. Air purifiers that are certified medical-grade HEPA are guaranteed and third-party tested for efficiency, including sealing

How to maintain an air purifier for maximum efficiency?

High-performance air purifiers like those offered by Eoleaf require minimum maintenance, but the maintenance that is required is essential in keeping your air purifier at peak operating performance.

For an Eoleaf air purifier, the only maintenance required is replacing your filter(s) at the recommended intervals. Eoleaf filters are durable and have a 12-month lifespan. Unlike other brands, all of our technologies and filter layers are contained within one convenient filter block, so there is no need to schedule multiple filter replacements throughout the year. Thanks to our UVC sterilization technologies that are included as part of our 8-step air purification technology, our filters are sterilized and, as a result, are safe to handle during filter changes.

The Eoleaf difference 

Eoleaf’s air purifiers offer the most advanced technologies on today’s market, including HEPA filters, activated carbon filters, all while serving simultaneously as an ioniser with photocatalysis and UV technologies. Find out more about our range of air purifiers here and refer to our in-depth Buying Guide for more information on our products. Additionally, if you need assistance while making your decision, we are here to help! Reach out to our team of experts with any and all of your questions. 

Frequently asked questions (FAQ)

Do air purifiers really remove dust and pet dander?

Air purifiers that are equipped with HEPA-certified filters (H13 or H14) are engineered to effectively remove at least 99.97% of fine and nanoparticles, including dust and pet dander, down to 0.01 microns. Ensure that the filter is certified, meaning that the filter has been third-party tested for its efficiency.

Are air purifiers effective for asthma and pollen allergies?

High-performance air purifiers with HEPA-certified filters (H13 or H14) have proven to be an effective way to improve asthma and pollen allergies. These air purifiers have been third-party tested for their ability to remove even the smallest fine and nanoparticles that are responsible for triggering asthma and allergy symptoms.

Should I leave my air purifier running 24/7?

How long you leave your air purifier running is entirely up to you and your air purification needs. Eoleaf air purifiers are durable and designed to be left running 24/7 if you so choose. Typically, it is recommended to leave your air purifier running 3-4 hours per day in order for the device to fully clean your indoor air and improve indoor air quality. 

How do I calculate the recommended room size for an air purifier?

In order to calculate room size for an air purifier, there are two metrics that are employed: CADR (Clean Air Delivery Rate, used to measure an air purifier’s filtration performance and speed) and ACH (Air Changes per Hour, or the number of times an air purifier completely replaces the air in a space with purified air). Use these simple equations below:

First, determine room volume.

Room volume (m3) = length (m) x width (m) x ceiling height of space (m)

• Example: a room measuring 6 m long by 4 m wide with a standard 2.5 m ceiling height

• 6 x 4 x 2.5 = 60 m3

Next, determine required air changes per hour (ACH). Regulatory bodies like the WHO and EPA state that in order for an air purifier to be considered effective, it must achieve an ACH of at least 3, meaning that it replaces all of the air in the space 3 times per hour.

Required air flow (CADR in m3/h) = room volume (m3) x ACH

• Example: 60 m3 x 3 = 180 m3/h

For a room of 60 m3 or 20 m2, an air purifier must offer a CADR of at least 180 m3/h. Always choose an air purifier that exceeds the recommended CADR to ensure that the air purifier can effectively clean the air in your space. For example, Eoleaf’s NeoPur 400, designed for smaller rooms of up to 40 m2, boasts a powerful CADR of 420 m3/h.

How often should HEPA and activated carbon filters be replaced?

Filters for Eoleaf air purifiers contain all 8 technologies within one convenient filter block. This means that there is no need to maintain multiple filter replacement schedules, a common practice found in other brands. Eoleaf filters are durable and designed to have a lifespan of 12 months.

Do air purifiers with air conditioning or heating functions really work?

Although the idea sounds like a good one, we recommend against investing in an air purifier that also provides climate control (2-in-1 or 3-in-1 devices). Air purifier filter mesh is highly sensitive to dramatic changes in temperature and humidity. Exposure to these elements may damage the fibers in the filter mesh and drastically reduce a filter’s lifespan and filtration capacity. It is recommended to invest in separate units for each of these purposes.

Are ozone-generating air purifiers safe for home use?

Ozone is a respiratory irritant and air pollutant that impacts human health. It is highly recommended to avoid purchasing a device that aims to purify the air with irritating pollutants. Instead, seek out an air purifier that is certified ozone-free.

How much electricity does an air purifier consume per month?

Eoleaf air purifiers are designed to be energy-efficient, consuming less than many air purifiers on the air purifier market and significantly less than standard home appliances. Our largest model, the AltaPur 700, does not consume more than a standard light bulb. It is recommended to leave an Eoleaf air purifier running in Automatic mode so that it runs mostly at its lowest fan speed. When it detects new air pollutants, its fan speed automatically increases until the pollutants are cleared.

References

 1 Engel, P., Barnes, C. (2022, September 20). Do air purifiers really work? CHOICE. Retrieved November 23, 2022, from https://www.choice.com.au/home-and-living/cooling/air-purifiers/articles/are-air-purifiers-worth-it

2 Catalina, T., & Feraru, A.-E. (2020). 8. experimental study of the impact of Air Purifiers on the indoor air quality inside of an apartment. Proceedings Of International Conference Building Services And Energy Efficiency, 84–92. doi:10.2478/9788395720413-008

3 Brągoszewska, E., & Biedroń, I. (2021). Efficiency of air purifiers at removing air pollutants in educational facilities: A preliminary study. Frontiers in Environmental Science, 9. doi:10.3389/fenvs.2021.709718

4 Dubey, S., Rohra, H., & Taneja, A. (2021). Assessing effectiveness of Air Purifiers (HEPA) for Controlling Indoor Particulate Pollution. Heliyon, 7(9). doi:10.1016/j.heliyon.2021.e07976

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6 Batterman S, Du L, Mentz G, Mukherjee B, Parker E, Godwin C, Chin JY, O'Toole A, Robins T, Rowe Z, Lewis T. Particulate matter concentrations in residences: an intervention study evaluating stand-alone filters and air conditioners. Indoor Air. 2012 Jun;22(3):235-52. doi: 10.1111/j.1600-0668.2011.00761.x. Epub 2012 Feb 4. PMID: 22145709; PMCID: PMC4233141.

7 Du L, Batterman S, Parker E, Godwin C, Chin JY, O'Toole A, Robins T, Brakefield-Caldwell W, Lewis T. Particle Concentrations and Effectiveness of Free-Standing Air Filters in Bedrooms of Children with Asthma in Detroit, Michigan. Build Environ. 2011 Oct;46(11):2303-2313. doi: 10.1016/j.buildenv.2011.05.012. PMID: 21874085; PMCID: PMC3161201.