What to look for in an air purifier?

All of us would like to breathe clean and fresh air all the time, wherever we are in the world. Unfortunately, the air outside is not as fresh as we would like. Instead, it is highly polluted and carries contaminants, most of which are invisible to the eye. These contaminants seep through our doors and windows and enter our homes, causing health hazards. Some parts of the country have higher levels of indoor air pollution than others.

However, every attempt is made to improve indoor air quality, leading to increasing demand for air purifiers. The market is saturated with many brands of air purifiers, with each one claiming top-notch performance. 

While it is good that manufacturers are able to put air purifying units on the market, it is also difficult to select the one that meets your needs. Air purifiers are not things that you can pick out without giving thought to your budget, features, customer reviews, etc., because it is for the long-term benefit of you and your family.

This guide is to make things easier for you to shop for an air purifier. It should tell you what would make an air purifier good and effective in cleaning your indoor air. But, before shopping for one, you need to know what to look for in your air purifier and if one or more air purifiers are needed for your home.

According to EPA, indoor air is two to five times more polluted than outdoor air. Pollutants such as tobacco smoke, dust, dust mites, mold, mold spores, and pet dander can all contribute heavily to poor indoor air quality. 

Air pollution comes from different sources, including the fireplace in winter, smoke from cooking, fungi, mildew, plant spores, pet dander, etc. It may not be possible to remove every single source, but it is possible to limit their entry into our homes, especially when there are family members with asthma and other respiratory conditions. 

Dust that is visible is around 10 microns in diameter. But, the dust of 0.3 microns can get lodged in your lungs. While proper ventilation can take care of some noxious gases and odors, you may still need an air cleaning system to help with other airborne contaminants.

How does an air purifier help?

air purifier benefits

Air purifiers use filters to reduce if not remove airborne particles from indoor air. It has been found that there is at least a 30% reduction in coarse airborne particles because of filtration.

A HEPA filter can capture and remove allergens that float in the air but may not be successful in dealing with heavier allergens that settle on the ground, such as mites, pollen, volatile organic compounds (VOCs), or mold. These airborne particles settle in little-noticed corners, and beneath furniture, they escape the filters. 

Even knowing this, it makes sense to use any system that can bring some control to the indoor air and resolve potential health problems. That is because an air purifier still does the job to ensure that a large percentage of allergens are removed from indoor air.

How many air purifiers should you have?

number of air purifiers

Knowing that the best way to improve indoor air quality is to eliminate airborne contaminants and ventilate the house with clean outdoor air is one thing. But, letting outdoor air inside can bring fresh air along with a few pollutants. Some parts of the house, like the basement, may not get enough fresh air. Other areas of the house also may be more prone to pollutants.

Therefore, the question of how many air purifiers you should have will vary depending on the size of the house and the rooms you use most often. i.e., the number of air purifiers you have depends on how many rooms you have, how much time you spend in each room, or if you want to have a whole-house air purifier.

Generally, three air purifiers with true HEPA filters are a minimum – one of the living room, kitchens, and bedroom.

Large homes may have more bedrooms, and you may need one for each of the bedrooms. If you have portable HEPA air purifiers, they can be moved from room to room and still give you sufficiently clean and purified air. 

How much should you spend on an air purifier?

money spent on air purifier

How much you should spend on an air purifier depends mainly on your budget. Different brands offer different costs. It also depends on the number of air purifiers you need. Is it for your whole house? Are you in an apartment? How many air purifiers are you planning to buy. These are some of the questions you will have.

The more air you need to purify, the costlier the air purifier. Therefore, you can buy a unit for less than $100 or one that costs over $1000.

Another factor to keep in mind is that you will be spending more on filter replacements in due course, your monthly utility bills, and maintenance, if necessary. The filters also vary between $20 and $80 or higher. For instance:

Mechanical, HEPA filters 

Mechanical filtration includes HEPA filters that are made of fine mesh. They are considered highly efficient; in fact, HEPA stands for high-efficiency particulate air. They work well in removing air contaminants and volatile organic compounds.

Activated carbon filter 

Activated carbon filters absorb molecules in the air. The difference between mechanical filters and activated carbon filters is that the carbon filter can eliminate odor from the air. 

UV germicidal irradiation

UVGI can kill viruses, bacteria, and fungi with ultraviolet light. UVGI is known for cleaning indoor air. It uses the UV-C band of the spectrum and can destroy the molecular DNA of bacteria and viruses. 

Ozone generators

Air purifying units that generate ozone can also remove air pollutants. But, ozone is not something that you want to breathe. So, it is better to have an air purifier that does not release ozone into the air. 

Electronic air purifiers

These electronic air purifiers also release ozone while cleaning the air of large particles in the air. They use electrostatic precipitators and ionizers to charge the airborne pollutants to make them stick to surfaces magnetically.

Ionic filtration

Ionic filtration technology releases a cloud of charged ions that attaches itself to the airborne contaminants, thereby forcing the contaminants to fall to the floor or any nearby surfaces.

Some of the ionic air purifiers include an electrostatic collection plate to attract the particles that can be removed from the room. It can remove contaminants of size .01 microns.


Photocatalytic oxidation uses UV radiation and a photocatalyst to produce hydroxyl to oxidize gasses. But, this type of filtration also releases ozone into the air.

Going to buy an air purifier for your home? Then don’t forget these 5 Important Factors!

important factors to know

Whether it is for your home, apartment, or a single room, there are a few factors to consider. You would need to start by listing your requirements. For instance, do you want the unit to absorb toxins and dust from your home? Or, is it to fight smoke from entering the indoor air? How big is the room, and how many air purifiers will you need to buy? Do you want it to be portable and have Smart features, as well? Apart from listing the answers to these questions, you can do your homework on the below factors.

Filter Type

Filters are an essential part of an air purifier. Understanding what each filter does or does not for indoor air quality is the first step. Some filters, such as the HEPA filter, trap 99.97% of air pollutants, including pet dander, dust, dust mites, etc., while an activated carbon filter removes smells emanating from the kitchen or from pets and cigarettes. Some air purifiers have a UV light to kill bacteria and remove dust particles.

When looking at filters, it would help to know about the various filtration technologies. Some air purifiers have one or more pre-filters to trap the larger air contaminants before the main HEPA filtration can do its job of eliminating the smaller particles.

It is a given that the type of filter is one of the primary factors to consider when looking for a high-quality air purifier. 

Air purifiers are priced based on their brand name, size, and filters. Therefore, your budget and household needs will have more to do with the decision.

Cleaning and maintenance costs also must be considered when you have a budget to fit in. It makes sense to consider the below five factors before buying an air purifier.

Power Consumption

Generally, air purifiers consume less electricity than other household appliances such as HVAC and even computers. Air purifiers can be left on to work 24×7, with only a marginal increase in utility bills.


Typically, a quiet air purifier is preferable to one that is noisy, especially in the bedroom. A noisy air purifier can disturb your sleep, which is why you need a unit that doesn’t have more than 40-50 decibels. 

Therefore, it is better to test an air purifier for noise levels because you have to live with the unit 24×7.

Safety for indoor air quality

Is an air purifier safe for you and your family? That is a factor to consider. The type of filter will also feature in the safety factor. Some filters produce ozone, and it is best to avoid them as they are more harmful in the long term.

Fortunately, you have the option to choose a good air purifier that only filters the air leaving you with fresh and ozone-free air to breathe. That makes it safe enough to invest in an air purifier for your home or a few of your most commonly used rooms.


While it is essential that air purifiers must be certified by Energy Star, AHAM, UL, and CARB, to qualify as a tested and certified unit, it may also make it a little more expensive.

Moreover, a manufacturer’s warranty of one or two years is always good to have because it is reassuring to have the company’s backing in case there are parts that need replacing. 

Apart from these five factors, air changes per hour (ACH), which refers to the number of times a unit recirculates the air after cleaning, is worth considering. For instance, the higher the ACH rating, the better the system is at cleaning the air.

The ACH rating depends on the size of the room. If the room is big, the rating of ACH will be lower. Air purifiers have defined air changes per hour mentioned on the product. There may be some variance as the unit may have been tested under ideal conditions. 

Yet another factor that plays into evaluating an air purifier is its clean air delivery rates (CADR). This rating indicates the unit’s capacity to remove three types of air pollutants – smoke, pollen, and dust. Similar to ACH, the clean air delivery rate defines the efficiency of the air purifier. The unit is more efficient if the CADR rating is high. 

What is the best HEPA air purifier to buy?

HEPA filters are considered the gold standard in air purifiers. It has a dense paper filter to trap all airborne pollutants making those air purifiers with a HEPA filter one of the top-end systems.

While there are many air purifiers claiming to use HEPA filters, only the True HEPA filter is certified to remove 99.97% of microscopic particles, even those as small as 0.3 microns.

The best HEPA air purifier is the one with a True HEPA filter, which removes mold spores, fungi, pollen, dust, pet dander, hair, and visible smoke. It is highly efficient and traps airborne particles making it safe for people with respiratory problems.

The Honeywell True HEPA whole room air purifiers are considered one of the top picks among air purifiers.

The Levoit Air Purifiers For Home are equally popular among customers and more affordable than others of similar capacity in the market. 

FAQ Section

1. How do you measure a room for an air purifier?

When measuring an area for the right-sized air purifier, you will need to know if the rooms are connected. In the case of connected rooms, you can measure the length and width of each of the rooms separately and add them.

For instance, if you have two connected rooms of 120 sq. ft. each and 80 sq. ft. in width, you will have a total square footage of 200 sq. ft. Your house plan will have the required measurements if you’re looking for a whole-house air purifier.

You can also go outside the house and measure the walls outside. Don’t forget to multiply this number by the number of levels of your home. You will need to include all levels of your house if you are going for the whole-house air purifier. Most air purifiers will clean the air efficiently if you get the right-sized units.

The ideal measurement for an air purifier is to get one that exceeds the size of the room.

2. Does it make sense to buy an air purifier only for the bedroom?

If you are only looking for clean air in your bedroom because that is the room you most frequent, it makes sense to get an air purifier only for the bedroom. However, that is rarely the case. Your living room and kitchen will have airborne contaminants that can easily spread to your bedroom.

The purpose of an air purifier will be defeated if you step out of one room only to be exposed to pollutants in and around the rest of the house.

3. What are the natural ways to purify air?

Indoor plants

Specific plants convert benzene and formaldehyde into oxygen. They are low maintenance and can be placed around the room to purify air naturally. 

Reduce sources of pollution

Products used in a house have chemicals, including fragrance. They are used in sprays and cleaning solutions. By reading the contents of each product, you can ensure that you can avoid using such products. 

Keep surfaces dust-free and clean.

Vacuuming away the dust from the carpet and other surfaces is always the best approach to clean indoor air. Rugs and carpets attract dust mites and allergens, and they are hard to remove without regular vacuuming.

Wiping the hard surfaces every day can also help indoor air. 

Use only beeswax candles.

Many households use candles to add a pleasant smell to the rooms. These candles are often made of paraffin and will release fumes. Swapping them for beeswax candles is a good idea. Make sure that the wick is not made of metals such as zinc and lead. 

Ventilate the rooms regularly

While outside air may bring pollutants into the house, it is still necessary to air out the rooms by opening the windows. It may be easier in some parts of the country with low air pollution levels.

Still, wherever you live, a little outside air needs to circulate indoors to ensure that the stagnant indoor air can be let out.

However, an ozone generator is harmful to both humans and pets alike. It is best to avoid ionizers for households with pets, as even the smallest amount of ozone exposure can cause permanent health damage for your pets.

4. How Much Maintenance Do Air Purifiers Require?

Air purifier maintenance includes regular filter changes. If you are running the air purifier constantly, you may need to change the filters once every three months. However, for any appliance to work at their optimum best, they need regular inspection and upkeep. An inefficient air purifier will also add to your electricity consumption as it draws more power to work. 

Wrapping Up

While you may realize that you need an air purifier in your home, you may not know how to select one or what you need to look for, in the unit. It is true that home appliance manufacturers attach the specifications to their labels and their user manuals; but, it always helps to know as much as you can about the air purification system and how to make the right investment in one. This article is a guide to familiarize you with air purifiers in general and to ensure that you go into the market armed with relevant information and buy the right air purifier for your needs.

There are a few main factors to consider such as filter types, certifications, size, and how much maintenance they require. It would help to keep these in mind along with your budget. The advantage to buying an air purifier for one room, i.e., your bedroom at first, is that you can take it slow and add air purifiers to the rest of the house on a monthly basis to make it easier on your wallet.

Whatever the approach, air purifiers have become more a necessity than a luxury in the wake of the pandemic and increasing air pollution.


About The Author

Olivia — a self-confessed air quality addict — is a home climate enthusiast, fresh air advocate, and someone with deep personal experience and knowledge about mold extermination. Her work was mentioned in countless notable humidity publications. Previously she was an editor at Mold Remediation.