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Air Purifier Buying Guide – What To Look For During Purchase?

Are you looking for an air purifier and getting stuck with varieties of unknown terms? Don’t worry. In this article, we will explain everything and help you pick the right option. Read the article carefully and take an intelligent decision before buying a perfect-fit air purifier.

Explanation of some common terms

When you try to investigative about air purifiers, you may confront some terms that are quite unfamiliar to you. Knowing the meaning of all the terms are not equally important but many of them indicate the usefulness of an air purifier. Find the meaning of some technical terms that you will see during your purchase.

TSS: The term TSS is an abbreviation of the ‘Thermodynamic Sterilization System’. This system purifies the air with the help of high temperatures – around 400o F. It features a ceramic core that produces heat so that contamination of air such as germs, viruses, bacteria, pollen allergens, and so on are killed or destroyed.

ENERGY STAR: You can find some air purifiers that are certified by ENERGY STAR. It indicates that those air purifiers are energy efficient. These have a nominal standby power to rated power ratio are safe for the environment. This certificate is provided by the U.S. EPA (Environmental Protection Agency) and also U. S. Department of energy.

AHAM certified: AHAM is the abbreviation of the ‘Association of Home Appliance Manufacturers’. AHAM provides the efficiency certificate of an air purifier. It measures the CADR of the air purifiers. CADR means ‘clean air delivery rate’. From CADR rating, we can know how effective an air purifier is to clean the air and catch the smoke, pollen, and dust.

Types of filter

The most important part or feature of an air purifier is its filtration system. Different types of filters are used by the manufacturers such as preliminary filter, carbon filter, HEPA filter, ULPA filter, ozone generator, and so on. Usually, the manufacturers of the air purifiers use two filters minimum on their filtration system. Some are natural and some produce chemicals or ozone. How would you understand which one is suitable for you? It depends. Generally, I prefer 100% ozone and chemical-free air purifiers. Important information is that air purifiers cant vanish airborne pollutants. It just traps or catches the contaminant particles.

The most common and useful filtration stage is the preliminary filter or pre-filter stage. The basic job of a pre-filter is to catch comparatively large airborne particles such as pet dander, hair, lint, and so on. Other than these, a pre-filter is used to protect the main filter. Some pre-filters are washable/ vacuumable, some are permanent and some are just replaceable. Usually, pre-filters are made of fibers but carbon made pre-filters are also popular.

The HEPA filter most is the most common main filter. HEPA means the ‘high-efficiency particulate air’. The standard of a HEPA filter is suggested by the American Lung Association (EPA). You can find various types of HEPA labels on the air purifiers, but only the True HEPA filters maintain the EPA standard. At the same time, some manufacturers offer the HEPA grade, HEPA type, or permanent HEPA filters. You should keep in mind that these types of HEPA filters are not the actual HEPA filters (although these are almost near to the HEPA standard). HEPA air filters can trap 99.97% of airborne pollutants such as pollen, germs, dust, and so on, as small as 0.3 microns. Some HEPA filters can catch smaller than 0.3 microns airborne particles but those are very costly and also not easily available.

Regular use of an air purifier may remove bad odors and smoke. For this purpose, manufacturers use activated carbon filters or charcoal filters. It can naturally absorb smokes, light chemical gases, VOCs, and nasty household odor compounds. These are very effective for smokers and useful for pet owners.

As an optional feature, some air purifiers provide extra filtration stages such as the ionizer, UV-C light, plasma wave, ozone generator, and so on. Most of these filters produce ozone or other elements that can affect your body, especially lungs and eyes.

Effective range or Coverage area

Before buying an air purifier, you should measure the size of your room where you want to set the air purifier. All air purifiers are not compatible with rooms of all sizes. Some are only for personal use or a desktop piece. On the other hand, some models are perfect for the whole house. To get the right coverage information, you have to check the air changing rate per hour. For specific square feet, the number of air changes per hour says the power of the air purifier. If you feel puzzled, you can buy a larger air purifier, if it does not cut your pocket.

CADR rating

Nowadays, most of the manufacturers provide their CADR (Clean Air Delivery Rate). CADR signifies the efficiency of an air purifier. This standard is provided by AHAM . More CADR offers more efficiency. As an example, CADR 150 (dust) means your air purifier can catch dust from the air at the rate of 150 cubic meters per hour. AHAM standardizes CADR for Smoke, Pollen, and Dust. Some air purifiers offer one CADR number for all 3 contaminant particles. On the other hand, some offer different numbers for dust, pollen, and smoke.

The standard of minimum CADR for 100 sq. ft is 60 ft3/min, for 200 sq. ft, it is 130 ft3/min, for 300 sq. ft is 195 ft3/min, for 400 sq. ft is 260 ft3/min, for 500 sq. ft is ft3/min and for 600 sq. ft is 390 ft3/min. It is highly recommended that you check the CADR before buying and ensure the minimum requirements.

Noise level

It is recommended to run your air purifier 24 hours. Therefore, the quiet operation of the air purifier is very important. Usually, the noise level of an air purifier is measured with the dB unit. Before making the purchase you should check and recheck the noise level.  Some models of air purifiers are enough quiet in a low fan speed mode but very harsh on high fan speed. In general, you can allow a maximum of 25 to 50 dB for lower fan speed. For higher speed, the allowable range can be 60 to 70 dB. If the manufacturer does not declare the height and lowest noise level, then it’s not a good sign. If you find a good quality budget-friendly air purifier with a buzzing sound on higher speed but quite quiet at a low fan speed level and if it offers a full sleep mode, it’s ok to buy. Run the machine at low fan speed all the time and try a higher speed when you are not at home. Noisy air purifiers are not suitable for pets and children.


Generally, people use air purifiers in different places. When you work in a kitchen you may need to move it near the kitchen. An air purifier may need to move near the litter box if you are a pet owner. During the sleeping time, you may want to place it in the bedroom or on show time in the living room. If you don’t have multiple air purifiers, you may want to move your single air purifier to many places. Therefore, an air purifier must be lighter. Before the purchase, please check the weight of the machine if you want it to be mobile. Besides, a lightweight air purifier is good for traveling, transporting, and storage.


Filters of the Air purifier are not permanent. You will have to replace them from time to time. Even those machines which come with the ‘Permanent’ tag also lose performance after a specific time and need to replace. Normally the maintenance cost of an air purifier varies company to company, even model to model. Usually expensive and good quality filters last a long time. On the other hand, poor and cheap filters need to replace very often. Most of the time, the disposable filters are superior to the permanent filters and therefore, recommended for asthma and allergic patient. The life span of a filter depends on its run-time and the pollutant density.

Before choosing a specific model, you can calculate the replacement cost per year. Sometimes, the maintenance cost of the budget-friendly models is much higher than that of the high-priced model. Therefore, compare both of these and keep your pocket healthy.

Energy efficiency

In general, an air purifier is suggested to run all day long. Therefore, it’s very important to check the energy efficiency of the machine you consider for your family. Usually ‘Energy Star’ certified models are quite energy-efficient. You should check the rated power, stand by power, fan speed power, and especially the sleep mode power.

Extra features

Although an air purifier is used to purify the air pollution but nowadays, some extra and smart options are also available with it. These extra features improve the utility of the machine. Various manufacturers may offer different types of additional features such as the auto-off timer, check filter indicator, night light, air quality sensor, remote control, wifi connection, smart device operation, and so on. But keep in mind that additional options will not increase the performance or efficiency of an air purifier. Always prioritize the performance over the bonus features.

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Final words

You cant find any single air purifier that is perfect for all. If you determine to buy an air purifier, you have to check the CADR rating first. If you found the CADR is OK then look at the filter quality and efficiency. When these two points match with your requirements, then investigate other qualities such as noise level, coverage area, dimension, weight, built-quality, portability, maintenance cost, and so on. You should also consider the design and color. If you think that our air purifier buying guide is helpful, please share with others. Have a good day!

2 thoughts on “Air Purifier Buying Guide – What To Look For During Purchase?”

  1. Good day,
    I’d like to ask, since my room is about 200 sq.ft, would this be a good air purifier for my room? ASIN B08JTK1C5Q, from Amazon.

    Looking forward to hear from you,


    • Hi Isaac. Thanks for the comment. Can not confirm you about the model you mentioned. Can you check at amz. Thx.


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