Do air purifiers actually work?

Do air purifiers actually work?

You may be having problems with air quality inside your home and you might be looking for an air purifier that can help you with certain health problems, such as asthma or allergies.

However with such a big variety of air purifiers and air ionisers on the market, it can be difficult to know what to look for, and if they actually do anything in the first place, right? 

In general, studies suggest that a good quality air purifier can effectively improve indoor air quality by removing the number of allergens and pollutants in the air, including pollen, pet dander, mould and other particles that may cause symptoms of asthma and allergies.  

However, before taking a closer look at these machines the important thing to note is that an air purifier alone cannot provide an adequate solution to poor indoor air quality and allergy issues.  It will not remove pollutants and allergens from the floor, carpets, surfaces or curtains.  Therefore, it should be combined with regular dusting, mopping and general cleaning. 

It is important that before making a purchase you do your own research and that you get the right kind of machine to address air quality issues that are specific to your situation.

Below we will look at how air purifiers work, different methods of air purification, how to choose the right machine for you and what to look for when purchasing one.

How do air purifiers work? Different types of air purifiers 

Air purifiers and sterilisers can use different technologies to clean the air.  Below is the overview of the main types that are available on the market.


HEPA-type, True-HEPA and activated carbon air filtration:


This type of air purifier usually consists of a True-HEPA or HEPA-type filter and a fan that sucks in polluted air into the machine.  As air moves through the air purifier, harmful airborne particles and pollutants such as dust, bacteria and mould are trapped in the filter and the clean air gets pushed back out into the room.

Air purifiers with combined HEPA and carbon filters are one of the most popular air purification solutions available on the market right now.  And it’s no surprise because HEPA filters have been around since the 1940s and were developed by the USA Atomic Energy Commission as an effective solution for dealing with radioactive particulate contaminants. 

Not all HEPA filters are the same, for example, a certified True-HEPA filter must capture a minimum of 99.97% of contaminants at 0.3 microns in size.  Particles of this size are air pollutants that come from traffic, chemicals and fossil fuels and are the hardest to remove out of the air.

HEPA based air purifiers are even more effective at removing larger particles such as PM10, PM2.5 and allergens such as pollen.

However, a HEPA filter on its own cannot remove VOCs (volatile organic compounds), so an activated carbon filter is added to an air purifier to combat strong odours, harmful gases and other gaseous pollutants present in the air we breathe.  These filters capture gas molecules on the surface of charcoal with a process known as adsorption.  Over time the filter gets contaminated and can no longer trap gaseous pollutants effectively and needs to be replaced.  If removing unpleasant odours is your main air concern, make sure that an air purifier uses enough carbon. 

Winix Zero PRO air purifier has been designed to offer a superior air cleaning solution to allergy and smoke pollution problems.  It features a genuine granulated active carbon filter with AOC™ technology (Advanced Odour Control) that provides greatly improved chemical fumes, gas and odour adsorption. 

Winix Zero Pro Air Purifier In The Living Room- Aerify

Air purifiers with HEPA and activated carbon filters can provide a good air purification solution for parents with young children, smokers, pet owners and people with asthma; however, there are situations when you don’t want to capture but kill airborne microorganisms, bacteria and viruses. 


Photocatalytic oxidation air sterilisation (PCO):


Photocatalytic oxidation air sterilisation technology was first designed by NASA in the 1990s at the Wisconsin Center for Space Automation and Robotics.  Researchers there wanted to find a solution for eliminating ethylene that accumulated around plants growing in spacecraft.  In their research study, they discovered that the solution for eliminating ethylene also removed other airborne organic compounds and neutralized bacteria, viruses, and moulds.

Photocatalysis might sound very complicated, but it works in a relatively simple way.  Let’s look at the basics.

In simple terms, when ultraviolet light shines onto a catalyst - titanium dioxide, it frees electrons which convert oxygen and water contained in the air into highly reactive hydroxyl radicals that break apart molecules of pollution into more harmless substances such as carbon dioxide and water. 


UV-C air sterilisation:


Most of the UV-C air purifiers on the market today combine ultraviolet light air sterilization technology with an air filtration system like HEPA.  The air is sucked in the unit by a fan and ventilated through a pre-filter, a HEPA filter and eventually a chamber with UV-C light bulbs.  These coated bulbs expose pollutants in the air to an ultraviolet light that damages their harmful DNA.  

However, according to the indoor air quality scientific findings resource bank, the effectiveness of UV-C light depends very much on the amount of time the pollutants are exposed to the light, the size of particles carrying the microorganisms, humidity of the air in the room and the design of the UV system.

Generally, studies have shown that the effectiveness of UV-C purifiers is mixed.  Based on the United States Environmental Protection Agency’s guide on indoor air cleaners, a properly designed air purification unit should be able to:

"Air purifiers reduce the viability of vegetative bacteria and moulds and to provide low to moderate reductions in viruses but little if any, reduction in bacterial and mould spores." 

UV-C air purifiers may have some benefits when it comes to neutralizing harmful bacteria and mould, however, they have the most important negative aspect associated with the transformation of the oxygen in the air into ozone that can potentially cause health problems.

Because of this, it is important to choose a non-ozone producing UV-C air purifier.  For the ozone to be produced the light’s wavelength has to be at a specific range of 160 to 240 nm.  Choose an air purification system that uses ultraviolet radiation with a wavelength outside the ozone producing range, for example, 254 nm.


Ionisation air purification:


Ionisation air purification technology works by generating negative ions which charge particles in the air and bond to dust and allergens.  

Many studies show that negative ions can efficiently remove particles including ultrafine ones. However, evidence shows that many factors can affect the efficiency of this air purification process.  The removal rate of particles is related to the pollutant’s size, its concentration and the ventilation conditions in the room.

If you consider buying an air purifier that uses ionisation, make sure that you choose a model that does not emit ozone and is certified by the California Air Resources Board (CARB).  This certification means that when tested an air cleaner complies with the federal ozone emissions limit of 0.050 parts per million. 

One of the top-rated air purification solutions based on the ionisation air purification technology is the IonFlow range from the Swedish manufacturer Light Air.  IonFlow air purifiers are ARB certified and use patented technology to clean air from the most harmful particles – fine, ultra-fine and nanoparticles.

LightAir IonFlow Signature Room Air Purifier - Aerify

Ozone generating air purification:

If you are looking for an air cleaning solution for your home we highly recommend that you do not use these devices and concentrate your search on air purifiers that use the technologies listed above.

According to the California air resources board, these devices purposely emit large amounts of ozone that can pose a serious health risk to humans by harming the cells in the lungs and respiratory airways.

Do air purifiers work for asthma and allergies?

According to the United States EPA, studies support that using HEPA air filtration may improve allergy and asthma symptoms.  Air purifiers help reduce harmful particles from the air that may cause symptoms of asthma and allergies.

The Lawrence Berkeley National Laboratory’s report on the health benefits of particle filtration suggests that many recent intervention studies report:

“significant improvements in health symptoms or objective health outcomes, particularly for subjects with allergies or asthma. The percentage improvement in health outcomes is typically modest, e.g., 7% to 25%”

However, an air purifier alone will not be able to remove all the allergens from the air and it may be required to work for a long time to see a reduction in allergy symptoms. That’s why source control and regular cleaning is also very important.  If you are allergic to pet dander, not allowing your pet into the bedroom and having a good quality air purifier working in the background while you sleep can help avoid exposure to the allergens and improve your wellbeing.

Do air purifiers work for dust, VOCs and other harmful pollutants?


Many air purifiers on the market are designed to effectively filter out the following air pollutants: dust, smoke, pollen, pet dander, hair and volatile organic compounds.  Each of the air cleaning solutions has different features, capabilities and downsides.  Some are very good at removing one kind of pollutant from the air, at the same time not being quite as efficient at removing others. 


Smoke is made up of two different types of pollution: particulate matter and VOCs.  

Air purifiers that use ultraviolet radiation are designed to kill airborne viruses and bacteria, but they are not as effective against any of the harmful components in tobacco smoke.  

HEPA filter air purifiers can remove the visible components of smoke including carbon, tar, oils and ash.  However, they are not effective at removing the rest of the harmful pollutants found in cigarette smoke such as VOS’s and highly toxic chemicals including carbon monoxide and hydrogen cyanide.  

Air cleaners with an activated carbon filter can remove gases, smoke, smells and odours from the air.  Contaminated air passes through an activated carbon filter, undergoes a process called adsorption and leaves the filter purified back out into the living space.  

Photocatalytic oxidation air sterilisers use ultraviolet and a catalyst that reacts with the light to produce catalytic molecules.  These molecules do not only remove gaseous pollutants from the air but actually destroy them by converting them into harmless by-products - carbon dioxide and water vapour.  


Many air purifiers with a washable pre-filter and a HEPA filter are a great solution for removing particles such as dust, pollen and pet dander.  However, no air purifier can make your home completely dust-free.  There are just too many sources of dust for a portable air purifier to remove them all.  Giving your home regular dusting is the best way to remove dust and other debris.


There are over 10000 chemical compounds that can be classified as VOC’s depending on the definition.  Many household products such as building materials, cleaners, paints and personal care products use chemicals that can be classified as VOC’s.

A HEPA air filtration on its own will not remove VOC’s, so an air purifier with an activated carbon filter is a good option for combatting these harmful gaseous pollutants.  


Air purifiers can trap mould spores with HEPA filters.  Under certain conditions mould spores can build up on the filter and eventually end up being emitted back into the living space.  For this reason, HEPA filters should be changed at a regular interval.

Should I get an air purifier?

According to the US environmental protection agency, we spend 90 to 95% of our time indoors, mostly in our homes, where the quality of air can be two to five times more polluted than outdoor air.  

Some of the bad stuff comes from the outdoors, however, some come from indoor sources, such as cooking, pets, second-hand smoke, consumer products, carpets and furniture.

The most effective way to reduce exposure to bad quality indoor air is to remove the sources of pollutants and regularly ventilate your home with cleaner outdoor air.  

However, if you are an allergy or asthma sufferer, air filtration can be an effective addition to source control and ventilation. 

Air purifiers and sterilisers are sophisticated machines designed to filter and neutralise polluted air in a single room or area, however, no air purifier will remove all pollutants, allergens and viruses from the air in your home.  

According to the US Environmental protection Agency,

“Using a portable air cleaner and/or upgrading the air filter in your furnace or central heating, ventilation, and air-conditioning (HVAC) system can help to improve indoor air quality.”

"Portable air cleaners and HVAC filters can reduce indoor air pollution; however, they cannot remove all pollutants from the air."

Bottom line

Air purifiers can help improve the quality of indoor air and help you with allergies but do not rely on them without creating any sort of household cleaning routine.

If you are interested in improving the air quality in your home take a look at our range of air purifiers designed to eliminate allergens, such as dust, pollen, pet dander, trap cigarette smoke, VOC’s and protect chronically ill from respiratory illnesses.

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