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Air Purifier Buying Guide | How Can I Buy the Best Air Purifier?

The sealed home environment makes people feel at ease, but it also faces the problem of air pollution. The air at home is five to ten times dirtier than the air outside. Americans spend 90% of their time indoors. Therefore, a high-quality air purifier is very important for health.

Buying the right air purifier can be confusing and frustrating. Some air purifiers currently on the market actually pollute the air with harmful levels of ozone, which is a strong lung irritant and is especially dangerous for asthma patients. Read this air purifier buying guide to learn about air purifiers and find a safe and effective device that suits your needs.

hosome air purifier

Common household air pollutants

Different air purifiers target different pollutants, so it is important to determine the pollutants to be removed from the home before buying an air purifier.

Airborne particles include pet allergens, dust mite allergens, pollen, plant spores, fungi, mold and tobacco smoke. They are the most common causes of indoor allergies and asthma attacks.

HEPA air purifiers are the best way to eliminate allergens in the air.

Household odors and gases include cooking odors, cat litter, tobacco smoke, various toxins and gaseous pollutants, such as indoor pesticides or aerosols. The activated carbon filter is very suitable for adsorbing those gases and odors that are too small to be captured by the HEPA filter.

Volatile organic compounds (VOC) are found in a variety of common household products: paints, varnishes, cleaning supplies, disinfectants, glues and adhesives, and even new carpets and construction supplies. Look for ingredients such as benzene, chloride, formaldehyde, ethylene, and toluene.

VOC can cause the following symptoms: irritation of the eyes, nose, and throat, headache, nausea, and even severe chronic health conditions such as damage to the nervous system. The presence of VOC can also exacerbate asthma.

Microorganisms include antigens, pathogens, bacteria and viruses. They are the everyday bacteria that make us sick. Mold is also considered a microbe.

Air purifier filter type

Different air purifier filters target different types of air pollution. HEPA air purifiers are the most popular. They are very suitable for eliminating household allergens such as dust, animal dander and pollen, but they are not very good at catching ultra-fine particles such as viruses or eliminating bad smells or chemical fumes.

Since different air purifier technologies have different advantages and disadvantages, many modern air purifiers combine two or more filter types in the same unit.

For example, Austin Air Super Blend Healthmate uses HEPA filters and activated carbon filters to help eliminate odors and smoke. Let's take a closer look at the different types of filters:

HEPA (High Efficiency Particulate Air) filters set air purification standards. By definition, HEPA filters can remove at least 99.97% of particles as small as 0.3 microns.

HEPA air purifiers were originally developed by the Atomic Energy Commission to capture radioactive dust particles. The HEPA filter only allows very small particles to pass through. Allergens such as pollen, animal dander, mold spores, and dust are trapped in the filter.

The main disadvantage of HEPA air purifiers is that you have to replace the filters regularly.

Main advantage: If it is HEPA certified, then you know it is working well. Not all HEPA filters are the same.

Size is important: the more square feet the HEPA filter has, the more particles it can remove. The size, material, and structure of the actual filter media all play a role in the air purifier.

Ionizers and ozone generators generate charged particles (ions) and emit them into the surrounding air. These ions combine with impurities in the air (such as dust), forcing the impurities to adhere to nearby surfaces.

Therefore, ionizers usually create dirty spots on nearby walls and floors because they cannot eliminate impurities; ionizers simply force impurities to adhere to the surface (just like static electricity can make socks adhere to shirts).

Ionizers are the second most popular type of air purifier, but they all release ozone, which is a strong lung irritant and is especially dangerous for patients with asthma and other chronic lung diseases, children and the elderly.

The working principle of electrostatic precipitator is the same as ion generator and ozone generator, but electrostatic precipitator captures impurities instead of simply forcing them to adhere to the outer surface.

Electrostatic precipitators, such as the Friedrich C90B electrostatic air purifier, use electronic batteries to charge the particles in the purifier and immediately trap the impurities on the collecting plate. The main advantage of this type of air purifier is that there is no need to replace the collector plate; they can be easily cleaned in the dishwasher. Please note that some electrostatic precipitators also produce ozone.

Charged media filters work in the same way as electrostatic precipitators, but they collect particles on fiber filters instead of plates. The advantage of these filters is that they can collect very small particles, sometimes as small as 0.1 microns, through a combination of filter and electrostatic charge.

The disadvantage is that, like electrostatic precipitator filters, charged media filters quickly lose efficiency, and they may require more frequent filter replacement than HEPA air purifiers.

These types of devices can generate ozone, but better devices on the market cannot. If you want to buy this type of air purifier, please make sure it does not produce ozone. The best air purifier in this category is the Blueair air purifier.

Activated carbon filters are rarely used alone to purify the air, but they are often used in conjunction with other filters. Activated carbon and charcoal filters excel at adsorbing odors and gases and neutralizing smoke, chemicals and fumes.

When materials adhere by chemical attraction, "adsorption" occurs. Activated carbon is treated with oxygen, opening millions of holes in the carbon. There are so many tiny holes that a pound of activated carbon has a surface area of ​​60 to 150 acres. This huge surface area makes it ideal for adsorbing gases and odors.

These chemicals and gases are too small to be captured by the HEPA filter, but they will bind to the huge surface area of ​​activated carbon. The larger the carbon filter, the more chemicals it can absorb and the longer it will continue to work. When it is full, it can no longer adsorb and must be replaced. The impregnated carbon filter contains an additional chemical substance ("chemical adsorbent") to eliminate certain chemicals, such as VOCs.

Antibacterial and sterilization filters can eliminate bacteria and germs. For example, the IQAir Clean Room H13 HEPA air purifier uses HEPA filters that have been treated with chemicals to kill microorganisms in the air.

Other air purifiers, such as the AllerAir 4000 EXEC ultraviolet air purifier, use ultraviolet lamps to kill bacteria. When antigens and pathogens pass through the lamp, it emits ultraviolet waves, changing their DNA, making them sterile and harmless.

Air purifiers with UV filters are usually used in sterile environments, such as hospitals, kitchens, daycares, and laboratories. In residential use, they are very suitable for controlling mold. If you are a person who is often sick, then an air purifier with a sterilizing filter may be just what you need to provide additional boost to the immune system.

The pre-filter removes large particles before the primary filtration. Almost all air purifiers are equipped with a pre-filter.

Other factors to consider before buying an air purifier

Covered area

Make sure that the area listed for the air purifier is approximately the same or slightly larger than the area of ​​the room where you plan to use it.

Air changes per hour (ACH)-This number, also known as the ACH level, tells us how often the air purifier exchanges all the air in a given room. For example, if the purifier has an ACH level of 6 in a 20' x 20' room, it can exchange all the air in that room 6 times per hour. If you have allergies or asthma, you want an ACH rating of at least 4, preferably 6 or 8.

Clean Air Delivery Rate (CADR)

The CADR calculated by AHAM (Association of Household Appliance Manufacturers) tells us not only how much air is purified, but also the degree of purification. Air purifiers that have passed the AHAM test should have an AHAM certified seal and CADR numbers for three pollutants: tobacco smoke, pollen, and dust.

The higher the CADR level, the better the air purifier's suppression effect on this pollutant. The CADR rating is fairly calculated and approved by the Environmental Protection Agency and the American Lung Association.


Air purifiers range from affordable air purifiers for $100 for small spaces to air purifiers with a full load of more than $1,000 for large rooms.

Filter replacement

If you buy a HEPA filter, don’t forget to check the cost of replacing the filter. If your device contains both HEPA filters and carbon filters or other combined filter media, they may need to be replaced separately and may last for different periods of time. This can be troublesome, especially if they are difficult to access.

Noise level

Some air purifiers, such as Blueair units, are very quiet, while others can be very loud when running at high power. If possible, ask for a demonstration before buying an air purifier.

Energy use

Like all electrical appliances, different air purifiers use different energy sources during operation. Unlike most appliances, air purifiers run continuously, so you need to consider water and electricity bills before buying an air purifier.

If only volts and amperes are listed, just multiply the two together: volts x amps = watts. A typical mechanical air filter can be used anywhere from as low as 50 watts to as high as 200 watts. (For comparison, a typical lamp uses about 60 watts, while a typical computer uses about 365 watts).

Air pollution

Some air purifiers pollute the air with ozone, which is a strong lung irritant and is especially dangerous for asthma patients, children and the elderly.

Extra features

These are bells and whistles. They can make your air purifier easier to use. On the other hand, they can also significantly increase the price of air purifiers, but they are actually not much better than the next one.

You just need to decide which features will make your life easier and which are not worth the extra money. For example, the filter replacement indicator can let you know when to replace the filter. If you plan to move the air purifier frequently, the handles or casters are important.

Manufacturer's reputation

The reputation of the manufacturer and past customer experience are worth considering in your decision. Certain manufacturers and products are highly respected in the industry for a reason, and the same is true for products that have received less respect. Check customer reviews to understand reputation.


A five-year warranty is a good choice. Ten-year warranty is even better! Consider the warranty coverage-motors, fans, electrical components?

In addition, understand whether certain customer actions will invalidate the warranty. If the customer does not purchase a replacement filter within the recommended time period, some manufacturers will void the warranty; if you plan to reduce the frequency of running the air purifier, or if the air in your home is cleaner than average, this may result in inconvenient.


Oct 19, 2021 • Posted by Mary OConnell

Need a replacement filter ASAP for Hosome Smart Wifi Hepa Air Purifier for Home. I believe it is the H13 True HEPA filter.
Please contact me.

Sep 20, 2021 • Posted by john weathers

have 2 kj210f looking for replacement filters
where do i get them and part number for it

Aug 11, 2021 • Posted by ronnie locke

need air filter for kj210f

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