How to Choose the Right Air Purifier

How to choose the right air purifier?

Are you wondering how to choose the right air purifier, and which one is suitable for you? There are several things to consider when choosing an air purifier. Very often, customers look at the area coverage specified for each individual air purifier. Manufacturers often have different ways of measuring this. Here, we show you what we believe is the correct way to determine the right area coverage for an air purifier.

There are many good reasons to buy a good air purifier.

• Allergies to pollen, dust mites, dust, mold
• Reduces urban pollution (traffic, road dust, diesel, wood burning)
• Protects against illness
• Protects vulnerable individuals (newborns, elderly, sick)

Assumptions for the guide

1. We assume that the filter can remove the particles you react to and want to get rid of. Today, most air purifiers use a HEPA filter, often combined with other purification methods.
2. We assume a normal ceiling height of 2.4 meters. If your ceilings are higher, you must consider that more air needs to be purified.

Determine the amount of air to be purified

We start with the area to be purified and multiply it by the ceiling height of 2.4 meters to find the volume.

Example: If you have a room that is 3.5 meters wide and 4.8 meters long, you have an area of 3.5 x 4.8 = 16.8 square meters (m²). You should multiply this by the ceiling height of 2.4 meters, so you get a volume of 16.8m² x 2.4 m = 40.3 cubic meters (m³). We now know how much air needs to be purified.

Determine how often this air should be purified

When the air purifier is running, air passes through the filter. How often the air passes through the filter matters.

• If you have minor problems, it is sufficient for the air to pass through the filter three times per hour.
• For medium problems, all the air in the room should pass through the filter five times per hour.
• If you have major problems, all the air should pass through the filter at least 7 times per hour.

So, we see that two factors are at play: the size of your room and how often you need to purify the air. Manufacturers often state the suitable area for an air purifier, but they don't consider whether your needs are small, medium, or large. The figure you can trust more is the fan capacity, and that's what we use as the basis for further calculation.

Check the air purifier's fan capacity

Almost all manufacturers state the fan capacity. This should be given in cubic meters per hour (m³ / hour). Common air purifiers often have a fan capacity of 200 to 400 m³ per hour. The greater the fan capacity, the more air it can purify.

Example

In the example above, we saw that your room is 3.5 m x 4.8 m = 16.8 m² (Square meters)

With a ceiling height of 2.4 meters, the volume is 16.8 x 2.4 = 40 m³ (Cubic meters)

You have normal air quality problems. Therefore, the air should pass through the filter five times per hour.
Your fan capacity requirement is therefore 5 x 40 = 200 m³ per hour.

You should therefore look for an air purifier with a fan capacity of at least 200 m³ / hour. Remember that most manufacturers state the fan capacity at the highest fan speed. When a small air purifier runs at its highest speed, it usually produces a fair amount of noise. If you are sensitive to noise, we recommend buying a slightly larger air purifier so that you can use it at a medium fan speed. This will give you good results without too much noise. Remember that if you don't run the air purifier at its highest fan speed, you won't get the effect stated by the manufacturer.

If you have the same room as mentioned in the example, but you have major problems with pollen, you should multiply by 7 or 8 instead of 5 times per hour. 40 m³ x 8 = 320 m³. In this case, you therefore need an air purifier that can purify at least 320 m³ per hour. You should find this number in the air purifier's specifications.

Additional advice and tips

• Most people buy an air purifier that is too small. If in doubt between two models, you should buy the larger one.
• Are you going to purify a large room? It might be wise to use two medium-sized air purifiers instead of one large one. The reason for this is that two small ones usually make less noise than one large one. In addition, two smaller air purifiers can be placed with some distance between them, and achieve a better purification effect. If you have a large air purifier in one place, it has to move a lot of air to purify the entire room. This creates more noise and can stir up more settled dust.
• An air purifier only purifies the room it is in. Many manufacturers state very optimistic figures for purification capacity. If you see an air purifier that claims to purify 100 m², you might easily think it will keep your entire apartment or house clean. Remember that an air purifier usually only purifies the room it is in. It cannot capture dust, pollen, and pollutants in other rooms. Some will move from room to room, but this is minimal. As a rule of thumb, we therefore say that the air purifier only purifies the room it is in.
• Use an air purifier where you spend the most time. Ideally, you should have an air purifier in every room, but this is rarely practical. Use air purifiers in the rooms where you are most often. This is usually in the bedroom, living room, and at work.
• Remember that even if you have a ventilation system with an air filter, this filter is often coarse and lets through small particles. These are the ones that are harmful to you. In addition, much of the pollution comes from inside, such as mold, dander, dust from textiles, and gases from furniture and renovations. A filter on the outside won't help with that.
• Remember to change the air filter! This may sound trivial. Nevertheless, we see quite a few people who buy an air purifier but forget to change the filter. An air purifier with a clogged filter has no effect. It can be a good idea to subscribe to a filter replacement service. That way, you'll remember to change it. You can find filters for your air purifier here.

How can I choose the right air purifier for me?

We often get questions about which air purifier is the best. It's not so easy to answer. There are many criteria to choose from. Some are good at one thing, while others are good at other things. Some emphasize one characteristic, while others emphasize something else. Here, we will give you some things to consider when finding the air purifier that is best for you. Here are some of the things you should consider:

• Filter type
• Filter size
• Airflow
• Price of air purifier and price of air filter
• Design
• Functions

Which filter do you need?

Most people are familiar with the term HEPA filter. This term does not describe how the air is purified, but only how well the air is purified. An effective air purifier often has multi-stage filtration, which means that the air passes through several different types of filters before being blown out again. Most air purifiers come with a fine-mesh pre-filter that can be vacuumed, for larger dust particles and impurities. Furthermore, you can choose air purifiers with, among others, HEPA filter, HPP filter, activated carbon filter, ionization, PlasmaWave®, CleanCel®, and aerOHeal®. How many stages of filtration you need largely depends on how much you want to purify the air, but an air purifier with a HEPA or HPP filter is definitely recommended.

HEPA filter

Most people are familiar with the term HEPA filter. This term does not describe how the air is purified, but only how well the air is purified. There are several classes of HEPA filters, depending on how well they purify the air. H13 removes more particles than, for example, H-11. At the same time, an H-13 filter will provide less airflow because it is denser. Read more about the difference between HEPA-11 and HEPA-13 here. In its popular meaning, a HEPA filter is a filter made of crisscrossing fibers where particles get stuck when they try to pass through the filter. HEPA filters are often called mechanical filters, as the particles attach mechanically to the filter. HEPA filters remove, among other things:

• Pollen, house dust, cigarette smoke
• Mold spores
• Traffic pollution
• Viruses and bacteria
• Pet dander and hair

Pre-filter and activated carbon filter

• Pre-filter that captures large particles. This can be easily cleaned and prevents the main filter from filling up with large particles.
• Activated carbon filter that removes odors and chemicals (VOCs) from the air.

Today, it is common to combine a range of filters to remove different things from the air. Most are built around a HEPA filter, with several additional functions. Remember that you must change HEPA filters regularly to maintain the effectiveness of the air purifier.

Design

Design and appearance are important for many. Does the air purifier fit your interior? Does it have a suitable color? Do you like the style? We are all different here, and you have to decide what you like.

Placement

Ideally, the air purifier should be placed in the middle of the room, but this is rarely possible. If you have a ventilation system, place it where the air from the ventilation system comes out (not where the air is sucked in). If you have old-fashioned wall vents, place it near them.

Also, figure out which room it should be in. If you're only getting one air purifier, it should be in the room where you spend the most time. This is usually the bedroom. Even if you sleep with an open window, this is often where much of the pollution comes in.

Also, remember that even if an air purifier is stated to purify 60 or 100 m², in practice it rarely purifies more than the room it is in. While a dehumidifier can dry out an entire home, since moisture easily moves through the air, an air purifier will only be able to purify the room it is in. In this sense, it may be better to have two small purifiers in separate rooms than one large one in the middle.

Price

There are large price differences for air purifiers. You can get them from 1,000 kroner for the simplest and well over 10,000 kroner for what is truly high-end. Jarle Karlsrud at Bedre Inneklima AS says that they sell the most air purifiers in the price range of 4,000 to 5,000 kroner, and that in this price range you often get a good air purifier that does a proper job.

Noise

Noise is important for many. Generally, we can say that a large air purifier at low speed is quieter than a small air purifier at full speed. Most air purifiers only produce fan noise, but this can vary from manufacturer to manufacturer. Many specify the number of decibels, and this says a lot, but sound is individual and different, and if you are sensitive to noise, you can be annoyed by variations in fan speed or small ticking noises that come and go. Buy a good quality air purifier!

Additional functions

Many air purifiers have several functions in addition to filters. These can include:

• Ionization of the air, to help capture particles and reduce odors
• PlasmaWave^®, aerOHeal^® and other solutions for neutralizing viruses
• Particle sensor
• Wifi and app connectivity

PlasmaWave

PlasmaWave is a feature found only in Winix air purifiers. PlasmaWave reduces odors, chemicals, and VOCs in the air. Read more about PlasmaWave here.

aerOHeal

aerOHeal is a system that purifies the air by neutralizing gases, chemicals, VOCs. It will also reduce unpleasant odors.

Hybrid solutions

As a rule, hybrid solutions, i.e., devices designed to do two things, are a bad idea. Often, too many compromises are made. Nevertheless, there are actually quite a few good hybrids in air purification. There are both humidifiers and dehumidifiers with proper HEPA filters, which clean the air well both while adding or removing moisture, or if used as a pure air purifier in other seasons. Here, there are often good deals if you can find something that suits your needs.

Air washer

There are humidifiers that purify the air through water. These are very effective humidifiers that also clean the air well. These are called air washers. Read and learn more about air washers here.

* = The air passes through the filter 5 times per hour

** = The air passes through the filter 3 times per hour

Want to know more about other things?

We have also written long and good articles on other topics. Read more about:

• Everything about humidifiers (adding humidity)
• What is the correct indoor humidity?
• Everything you need to know about dehumidifiers.
• Choosing the right fan.