Do air purifiers actually work?

Do air purifiers actually work?

You may have air quality issues at home or you may be looking for an air  cleaner to help you with some health problems, such as asthma or allergies.

However, with such a wide variety of air purifiers and air ionisers on the market, it can be difficult to know what to look for.  Do they really do anything at all, 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 eliminate contaminants and allergens from floors, carpets, surfaces or curtains.  As a result, it must 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 see how air purifiers work, the various methods of air purification, how to choose the right machine for you and what to look for when buying 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 the 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 in the market at the moment.  And it’s no surprise because HEPA filters have been around since the 1940s.  They 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 True-HEPA certified filter must capture a minimum of 99.97% of contaminants at 0.3 microns in size.  Particulates of this size are air pollutants that come from traffic, chemicals and fossil fuels and are the hardest to remove from the air.

HEPA-based air purifiers are even more effective in eliminating larger particles like PM10, PM2.5 and allergens like pollen.

However, a HEPA filter on its own cannot remove VOCs (volatile organic compounds). An activated carbon filter is added to an air cleaner to combat strong odours, harmful gases and other gaseous pollutants in the air we breathe. These filters capture gas molecules on the surface of the charcoal through a process called adsorption. Over time, the filter becomes contaminated and cannot efficiently trap gaseous pollutants and must be replaced. If eliminating unpleasant smells is your primary concern for air, make sure that an air purifier uses enough carbon. 

The Winix Zero PRO air purifier has been designed to offer a superior air cleaning solution to allergy and smoke pollution problems.  It features a true pelleted active carbon filter with AOC™ (Advanced Odour Control) technology that greatly improves chemical emissions, gas adsorption and odours. 

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 in which you do not want to capture, but kill airborne microorganisms, bacteria and viruses.  


Photocatalytic oxidation air sterilisation (PCO):


Photocatalytic oxidation air sterilisation technology was first developed by NASA in the 1990s at the Wisconsin Center for Space Automation and Robotics.  The researchers wanted to find a way to remove the ethylene that was accumulating around plants growing in spaceships. In their study, the researchers found that the solution for removing ethylene also eliminates other organic compounds in the air and neutralises bacteria, viruses and moulds.

Photocatalysis can seem very complicated, but it works quite simply. Let's see 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.  These radicals separate pollution molecules into safer substances like carbon dioxide and water. 


UV-C air sterilisation:


Most UV-C air purifiers on the market today combine ultraviolet light sterilisation technology with an air filter system such as HEPA. The air is drawn into the unit by a fan and ventilated via a pre-filter, a HEPA filter and finally a chamber with UV-C bulbs. These coated light bulbs expose air contaminants to 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.

In general, studies have shown that UV-C purifiers have a mixed effect. 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 bacteria and mould spores."  

UV-C air purifiers can have some advantages when dealing with harmful bacteria and moulds.  However, they have the most significant negative aspect associated with the transformation of oxygen in the air to ozone which may potentially cause health problems.

For this reason, it is important to select an ozone-free UV-C air cleaner.  For ozone to occur, the wavelength of light must be between 160 and 240 nm.  Select an air purification system that uses ultraviolet radiation with a wavelength outside the ozone production range, such as 254 nm.


Ionisation air purification:


Ionisation air purification technology produces negative ions which charge particles in the air and bind to dust and allergens. 

Many studies show that negative ions can efficiently remove particles, including ultrafine ones. However, evidence indicates that many factors can affect the effectiveness of this air purification process. The particulate elimination rate depends on the size of the pollutant, 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 purifier conforms to the federal ozone limit of 0.050 parts per million. 

One of the best-rated air purification solutions, based on ionisation air purification technology, is the IonFlow range by the Swedish manufacturer Light Air.  IonFlow air purifiers are CARB certified and use patented technology to clean the air from the most dangerous particles – fine, ultrafine 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?

Studies by the U.S. EPA confirm that the use of HEPA air filtration can improve allergy and asthma symptoms. Air purifiers help reduce harmful air particles that can cause asthma and allergic symptoms.

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. It may be required to work for a long time to see a reduction in allergic symptoms. Because of this, source control and regular cleaning are 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 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 efficiently filter the following air contaminants: dust, smoke, pollen, pet dander, hair and volatile organic compounds.  Every air cleaning solution has different characteristics, capacities and disadvantages. Some are very good at eliminating one kind of pollutant from the air while being less efficient at eliminating others. 


Smoke is comprised of two different types of pollution: particulates 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 air purifiers can remove visible smoke components such as carbon, tar, oils and ash. However, they are not effective in eliminating the remainder of harmful pollutants present in cigarette smoke, such as VOS and highly toxic chemicals, including carbon monoxide and hydrogen cyanide. 

Air purifiers with an activated carbon filter can remove gases, fumes and odours from the air. The contaminated air passes through an activated carbon filter, undergoes a process referred to as adsorption, and leaves purified back into the living space. 

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


Numerous air purifiers with a washable pre-filter and a HEPA filter are an excellent solution for eliminating particles such as dust, pollen and pet dander. However, no air cleaner can make your house entirely dust-free. There are too many sources of dust for a portable air cleaner to eliminate them. The best way to get rid of dust and other debris is to dust your home regularly.


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

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


Air purifiers can trap mould spores by means of HEPA filters. Under certain conditions, mould spores can build up on the filter and eventually be released into the living area. For this reason, HEPA filters should be changed at regular intervals.

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 2 to 5 times more polluted than outdoor air.  

Some of the bad things come from the outside, however, some come from indoor sources, such as the kitchen, pets, second-hand smoke, consumer products, carpets and furniture.

The most effective way to reduce exposure to poor indoor air is to remove sources of pollutants and regularly vent your home with cleaner outdoor air. 

However, if you suffer from allergy or asthma, air filtering can be an effective addition to source control and ventilation. 

Air purifiers and sterilisers are sophisticated machines designed to filter and neutralise the 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 improve indoor air quality and help you with allergies, but don't rely on them without creating any kind of domestic 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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