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Air Purifier Buying Guide

Air Purifier Buying Guide

A good air purifier buying guide will help you identify which air purifier is right for you. Some air purifiers are great for one thing but not another. Some technologies work and some do not. Our air purifier buying guide will help you identify what to look out for and help you find the right air purifier for your needs.

Frequently Asked Questions

The first thing to consider before buying an air purifier is what you want to use the air cleaner for. Whether you want to reduce your allergy or asthma symptoms, remove tobacco smoke or dust from the air or simply want to create a healthier indoor environment - a good air purifier is often the best/only proper solution for airborne contamination. For their ability to take the broadest range of pollution out of the air, air purifiers are an ever increasingly popular household item. Air purifier buying guide - Common concerns and symptoms:

  • Asthma
  • Dust Mite
  • Removing Dust
  • General Air Quality
  • Traffic Pollution
  • Hay-fever
  • Mould
  • Pet Dander
  • Pollen
  • MCS (Multiple Chemical Sensitivity)
  • Cigarette Smoke

HEPA Air Purifiers
Certain things are considered ‘must haves’ for a good air purifier. An effective air purifier has, for example, the relevant filters to eliminate or significantly reduce the types of pollution in your home that you are concerned with. The air cleaner will also need to be able to complete an appropriate number of air changes within the room you are planning to use it in. Unfortunately, a vast majority of air purifier manufacturers are wilfully misleading in regard to the performance of their air purifiers. Things such as filtration efficiency, amount of airflow, noise level and what types of pollution the air cleaner can cope with are often obfuscated by many manufacturers – either because they do not know much about air purification or because they do not want you to know the truth about the performance of their product. What filtration efficiency, airflow and sound pressure you require, or is right for you, depends on your particular concern. We will discuss each performance indicator in the section below in more detail.

Some features of an air purifier are not absolutely necessary, but can be considered ‘nice to have’. A filter life indicator is, for example, a very useful feature to have. The filter life indicator will notify you when the filters need to be changed. Replacing the filters at the required time will ensure the air purifier is performing as it should and protects the fan from being damaged.

Unfortunately, there is no decent air purifier that is small enough to fit in the palm of your hand and can be carried around easily. Why not? Well, there are limits to the physics of what is possible. You would not expect a washing machine the size of a toaster to be able to do a proper load of laundry. Similarly, you should not expect an air purifier the size of a toaster to be able to move enough air to be able to properly purify an averaged size room. Casters can help make it significantly easier to move your air purifier around the house, particularly if you have a unit that can handle large amounts of air. Handles are also useful, as it enables you to easily lift the unit from one room to another.

Remote Control
Allows you to easily control and change the settings of the air purifier from a comfortable distance, increasing accessibility.

Filter Availability
Unfortunately, we see it all the time that even the big companies with household names make air purifiers without providing a guarantee for how long you will be able to purchase replacement filters. Once the unit is not selling well any more, or they feel it is time to “upgrade” it and change its looks and features, the model and the production of the replacement filters for it can be discontinued.

Timer Settings
Turning the unit on and off during times of the day/week enables you to save energy and prolong the filter life.

Multiple Fan Speeds
Alter the speed setting to your preference, to suit your indoor pollution level or sound preference.

Ionic air purifiers are marketed as being quiet and efficient; however, they also tend to release ozone into any room, not making them ideal for everyone.

Ozone Generators  Be wary of air purifiers that are straight up ozone generators. These units produce large amounts of ozone by design and form a serious threat to your health.

UPLA  Some air purifiers use a filter density known as Ultra-Low Particulate Air (ULPA), claiming that is superior to HEPA (High-Efficiency Particulate Air). These filters drastically reduce airflow and as such limit the performance of the air purifier.

Incineration and Combustion  This type of filter technology does not take pollution out of the air, but simply burns it. Burning dust and other pollution in the air does not directly lead to cleaner air… also, whilst incineration does not allow you to move very much air quickly – a key requirement for any decent air purifier.

Warranty  Any air purifier you purchase in the UK should come with a 2-year warranty; some air purifier manufacturers try to sell you an additional extended warranty or try to get your contact details in return for additional warranty. Be sure to check what the warranty covers, such as motor/ fan, display, other electrical components and labour. Consumables, such as filters are normally not covered by an air purifier warranty. Also, be sure to check if customer action will void the warranty. Most warranties will for example only apply to the original purchaser of the unit and will not transfer to subsequent owners.

Filtration Efficiency  As you can see from the table below, different concerns require different filtration efficiencies. The higher filtration efficiencies are achieved by HEPA or HyperHEPA filtration (as long as it applies to the whole system filtration efficiency and not just a ‘theoretical’ filter efficiency) whilst lower filtration efficiencies are achieved from using filters with a lower filtration efficiency such as ‘HEPA-like’ or ‘HEPASilent’ filters. It is very common that manufacturers do not display the actual filtration efficiency of the air cleaner as a whole, but only provide customers with a misleading theoretical filtration efficiency. If ionisation is used then it is worthwhile to know that the filtration efficiency will decrease the more polluted the collection surface/filter gets. The performance of the unit can drastically decrease because of this. Furthermore, if the unit is not leakage free, the level of leakage will increase as the filters become more loaded too, further decreasing efficiency. Thus, some ionisers will have a high filtration efficiency to begin with but after some time the filtration efficiency will gradually decrease.

 Whole system Filtration efficiency - 75%Whole system Filtration efficiency - 95%Whole system Filtration efficiency - 95% or higherCarbon/ MashCarbon/ Coconut BaseActivated Granular Carbon 2-3 KgActivated Granular Carbon 3 Kg or Higher
Dust Mite
Removing Dust
General Air Quality
Pet Dander
Traffic Pollution
Cigarette Smoke


Noise  The noise level will vary depending on the speed setting the unit is being used on. It is important to consider your noise tolerance and take into consideration where the air cleaner will be used. All proper air purifiers will produce some level of noise; depending on the speed setting the unit is being used on. However, you should not compromise the cleaning performance of the unit for the comfort of reduced noise levels. A fan that is too small or that is moving too slowly may not be pushing enough air to properly filter the air within the room it is being used in. One thing to be wary of is if manufacturers are not specifying the noise level on different speed settings of the air cleaner. It is unfortunately quite common for some manufacturers to market their air cleaner only on the noise level of the quietest settings. Depending on the technology used, some air purifiers are quiet at first but become noisier the more used the filters are. If the filters are loaded, then the unit will emit more noise as the unit is working harder, trying to pull air through the filters. To find out more about assessing the noise levels of an air purifier visit our Blogpost Quiet Air Purifier.

Research  Online research can be helpful; however, it is often difficult to say how liable a source actually is. Some sites are not particularly knowledgeable about air purification. Some formerly independent review sites have been bought by air purifier manufacturers, and now trying to promote their own products as the best. Here is a list of sites that do independent air purifier testing:

  • Consumer Search
  • Consumer Reports
  • Best Buy

To see a review of some of the best air cleaner testing sites, visit our air purifier reviews.

Maintenance Regularly maintaining an air purifier is important to ensure the unit is working effectively. In order to achieve maximum performance from the air purifier, you will need to replace the filters regularly. You should find out the cost and average life span of each filter before purchase. However, keep in mind that actual filter life will greatly depend on usage and contamination levels. Be wary of air purifiers which require very frequent filter replacements. Also, look out for air purifiers which require you to clean/or wash the filters.

Manufacturer's Reputation  The manufacturer’s reputation is an important deciding factor, as the experience of past customers deserves some consideration. Some manufacturers and products are highly respected in the air purifier industry for a reason, building their portfolio over the years through products which work and providing great customer service. You will always find manufacturers who make various claims about their products but have very little to support these claims.

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