Air Purifier Buying Guide

So you’ve been meaning to buy the best portable room air cleaner for home use you can afford. But it doesn’t feel like you know enough about room purifiers — yet.

Luckily you’re here.

The comprehensive air purifier buying guide (hopefully) you’re about to encounter answers every question you’re asking. This air purifier shopping guide will help you avoid many pitfalls on your way to your destination. Your destination is no doubt clean, healthy indoor air.

Once you’ve devoured this guide, your confidence around air purifiers will soar. You’ll start feeling like a smart shopper, someone who knows what they’re doing.


Particle Sizes



I’ll be talking about particles a lot in this comprehensive air purifier buying guide. Why not introduce you to a few of the most common particles at this point?

Here’s a table to help you know how big some of the most common particles are.

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Particle Sizes Expressed in Microns


So how big is 1 micron? As the name suggests, a micron is a measure mostly used to express the size of microscopic particles. But that doesn’t mean all particles described using this measure can’t be seen with the naked eye.

According to The Engineering ToolBox, the naked eye can’t see anything that’s smaller than 40 microns.
A micron = (1/254,000) inches. In other words, 1 inch is exactly equal to 254,000 microns. 1/25400 inches is also equal to roughly 0.00004 inches.

To put this into some perspective, a human hair is about 40 microns in diameter or 0.0016 inches.


What Does All this Mean?


You can’t see the vast majority of particles darting across the room every passing second. Good news: Some of the best air purifiers have been tested and found able to remove a substantial number of microscopic particles.

Some manufacturers (after testing) claim that certain air purifiers can even remove particles as small as 0.1 microns. In this comprehensive air purifier buying guide, I’ll mainly focus on what HEPA air purifiers are known to handle excellent. That is, particulate matter 0.3 microns in size or larger.


What Air Purifiers Don’t Handle Very Well


Contrary to what many manufacturers say, air purifiers aren’t excellent when it comes to removing gaseous pollutants. That’s why CADR focuses on how well a portable room air cleaner eliminates particulate matter rather than gaseous pollutants. More on CADR later.

But that’s not saying these products don’t remove gases and odors. They do. In fact , some air purifiers remove air contaminants down to 0.1 microns. I’ve even seen research that says that True HEPA air purifiers can filter airborne contaminates down to 0.01  microns. You can access this research in an article I’ve published on this site. Here’s the article: Do air purifiers remove PM2.5?

User experiences also indicate that these machines may help with gaseous pollutants. Visit Amazon or any other trustworthy online marketplace if you can. You’ll encounter lots of anecdotal evidence regarding these claims. And when a user says something is working for them, no one should ever say they’re lying. In fact, no research findings on Earth trump personal, actual experience with a product. I, too, own an air purifier. And I’d agree that they reduce smells to quite some extent.

Many air purifier users have reported that their product helped them handle different kinds of odors and gaseous compounds. They say their device sucked substantial amounts of tobacco smoke, cooking and pet odors, VOCs, and even nitrogen dioxides. But these machines certainly don’t eliminate gaseous pollutants as effectively as they do particulates.


What are Air Purifiers?


Air purifiers are devices designed to help remove (mainly) particulate matter from indoor environments. Many of the best air purifiers use True HEPA filters that effectively remove 99.97% of particles not larger than 0.3 microns.

It’s important to remove particles from your indoor air. But I vacuum-clean my home twice a month and dust regularly, you say. That’s great, and it eliminates tons of particles. But hygiene may not eradicate bacteria, viruses, smoke, VOCs, pollen, dust mites, and spores.

Did you know that the air inside your home could be way more contaminated than the air outside? The U.S. Environmental Protection Agency says that indoor air pollution is 2– 5 times more polluted than ambient air. “Ambient air” is an educated way to refer to outdoor air.

What’s more, the average person in the U.S. is at home 90 percent of the time. And 100% of the time, the average person is breathing! How clean is the air in your home?

Later on in this comprehensive air purifier buying guide, you’ll learn 7 shocking air pollution facts. After you lean the facts, you’ll want to take action immediately.

You Can’t See Microscopic Pollutants, but….

Just because you can’t see pathogens and other dangerous participles suspended in your indoor air doesn’t mean they’re not there. It just means you can’t see them. It also means you should find an effective means of removing them. And that’s where air purifiers come in.

Breathing dirty air is known to cause myriads of complicated illnesses including COPD, cardiovascular disease, and cancer. That’s why you want to inhale clean air most of the time.


Types of Air Purifiers


There are two main categories of air purifiers namely:


1. Whole-house air purifiers and,

2. Portable Room air cleaners/purifiers


1. Whole-house Purifiers


Also known as central air purifiers, whole-house air purifiers are house-wide purification systems that offer nonstop indoor air purification. Well, some systems stop working as soon as the HVAC system stops working.

Normally, these systems are added to a home’s HVAC system and can set you back quite some money. Are they effective? Yes, especially if they’re using high-MERV HEPA filters.

Note: not all HVAC systems are designed to use HEPA filters. In most cases, you have to hire an expert to make certain modifications. One more thing: HEPA filters for whole-house systems aren’t True HEPA filters. In other words, they’re not excellent when it comes to removing allergens and pollutants.

But sure, they work. As long as your HVAC system is well-maintained and you’re using high-quality filters, you’ll see less allergens, toxins, and other particles.

One advantage of using a whole-house system is that it’s a low-maintenance deal. That’s because these purification systems depend on your HVAC system for power. You won’t see bloated electric bills after installing such a system. In addition, their filters can last up to 5 years.


3 Types of Whole-house Air Purifiers


There are 3 main types of whole-house air purifiers. The only difference between them is the way their installation is done. There are standalone systems, duct-based systems, and filter-based systems.

Duct-based Whole-house Air Purification Systems

Normally, homework owners hire an expert to incorporate this filtration system into the HVAC system. There are 2 main types of duct-based systems. These are supply air systems and return air systems.

Return Air Systems


A return air system encounters air from your house before it (air) gets cooled or heated. Your HVAC expert should install the system at the point where air enters the furnace from the house. With this system, it’s best to use a media furnace filter.

Why not the usual flat, 1-inch filter? We’ll very soon see why.


Stay Away from Flat, 1-inch Filters


Many people choose to use the flat 1-inch filter for a reason — to save money. Usually, such people install a filter with a high MERV because they’ve been told it’s the best filter. So they go with a 1-inch filter that has a MERV rating of 12.
And it’s great. That’s because the MERV-12 filter keeps your HVAC system protected from dust and other material. At the same time, it keeps your indoor air clean.

But there’s a small issue.

A high MERV filter of this kind tends to raise your HVAC system’s static pressure. When that happens, your home won’t be very comfortable. Plus, you’re likely going to have trouble with your system down the road. The other issue is that using such a filter reduces air flow. And that isn’t a good thing.

Any alternatives?

Use a filter with a lower MERV rating, right? Well, such a filter keeps your HVAC system protected from dust and stuff. However, the filter won’t do much about other contaminants in your home.

There’s one more reason to stay away from 1-inch flat filters: they’re just not good handling odors.
Note: MERV is an abbreviation for Minimum Efficiency Reporting Value. It’s a measure of a filter’s air cleaning ability.


The Greatness of Media Filters


With these filters, you enjoy the benefits of high-MERV air purification while avoiding static pressure and reduced air flow.

Media filters are much better because they demonstrate better air filtration. That’s because they have a greater surface area than ordinary filters.

In addition, changing these filters is relatively easy depending on where the whole-house system is installed. Also, media filters are quite affordable.
Finally, with media filters, you can easily upgrade to higher-MERV filters for even better performance.

How Long Do Media Filters Last?


Media filters last about 12 months. But they may not last that long if you’re running your HVAC all the time.

Supply Air Systems


As the name suggests, supply air systems pump air into your house. The system is installed somewhere between the vent and furnace in the HVAC system.

This filtration system cleans the air before pushing it to your home. And it uses a process known as pressurization. The system draws air from outside your home into your indoor environment, creating positive pressures in the process.

As a result, the air inside the house exits via openings and cracks. And where vents and ducts exist, the air might exit through them. It may also leave via open windows. Basically, the system focuses on improving your home’s ventilation.

These systems aren’t expensive. And that’s a good thing.

However, some of these systems won’t ventilate the house if the HVAC isn’t running. Luckily, you can find modern systems that solve this problem.

Another issue is that these systems aren’t very efficient. That’s because they rely on your HVAC’s ducts which aren’t designed for ventilation purposes.


2. Filter-based Systems


Integrating filter-based systems into your HVAC system requires professional expertise. The system eliminates particulate matter from indoor air via a process known as electrostatic precipitation. This process applies voltage to particles, charging them. Charged plates in the system then attract these charged particles since they have an opposite charge.

There are some problems with this system, though. The first one is that the plates become dirty over time. And that renders them less effective. The other problem is that this whole-house system generates ozone.
Now ozone is a common air pollutant. It forms a huge part of smog, a worrying phenomenon seen in lots of cities today.

Ozone is an asthma trigger. It may also terribly irritate the lungs while lowering their efficiency. In fact, research links ozone to asthma attacks. The Asthma and Allergy Foundation of America states that ozone leads to increased emergency asthma treatments and meds usage. Evidently, you should stay away from any purifier or whole-house system that emits ozone.


3. Standalone Whole-house Filtration Systems


As the name suggests, a standalone whole-house filtration system isn’t a part of the HVAC system. Qualified technicians install this system in places such as attics. For the system to work effectively, experts include an additional air intake and exit system.
Note: Some people confuse extra-large portable air cleaners with whole-house air purifiers. Understand that there’s no such thing as a portable purifier that’ll clean every nook and cranny of your home.


Popular Whole-house Air Filtration Brands


• Holmes
• Whirlpool
• Honeywell
• GE
• Hunter


2. Portable Room Air Cleaners


These are standalone air cleaning units you can move from room to room as the need arises. Some are quite light while others are relatively heavy. Most of them have carrying handles and others have wheels (usually the heavy ones).

5 Common Types of Room Air Purifiers


Let’s dive right in.


1. True HEPA Purifiers


True HEPA filters are quite popular if not the most popular air cleaning devices these days. That’s because they’re super effective at what air purifiers do — removing air contaminants.

Don’t be fooled: not all manufacturers incorporate True HEPA filters into their products. You don’t need a purifier that uses HEPA-like filters. You need one that uses genuine, high-quality HEPA filters. More on the history and superiority of True HEPA filters later.

These purifiers often work hand-in-hand with a carbon prefilter. The prefilter handles some of the purification work, leaving less work for the HEPA filters. As a result, the HEPA filters tend to last longer.

Carbon prefilters are designed to remove gases, VOCs, and odors. They’re also effective at removing relatively large particles from dirty air.


Double Filtration


Typically, True purifiers offer what’s known as double air filtration. Phase #1 of the process happens at the prefilter while phase two happens at the HEPA filter.

One more thing: these devices use just one prefilter in most cases. As for True HEPA filters, some purifiers use one, others two, and others three. In general, the more the filters, the higher the machine’s power.

Washable Filters vs Non-Washable Filters


Some units feature washable filters while others use non-cleanable filters. Non-washable filters need to be replaced regularly. Typically, the prefilter is replaced once every 3 months. For HEPA filters, you’re looking at one or two replacements a year.

You should know that some of the better True HEPA purifiers can be quite expensive. On top of that, filter replacement costs can pile up to quite some amount over time.

Sure you can buy knockoffs or find creative ways to save on replacement costs. But there’s no way to completely eliminate maintenance costs.

That said, most models are reasonably priced and use affordable filters. So there’s nothing that stops you from accessing the True HEPA advantage.

Note: Some HEPA purifiers generate ozone. Sure, low ozone levels may not harm you. But it’s best to avoid ozone generators if you’re allergic to various triggers or have asthma.

2. Activated Carbon Purifiers


Activated carbon purifiers use filters made from carbon in granular form. These filters happen to be incredibly porous and offer a large surface area for adsorption.

These kinds of room air cleaners are known to be quite good at eliminating gases, odors, smoke particles, and even VOCs (Volatile Organic Compounds). With these purifiers, “seen with the naked eye” particles also get trapped in the carbon filter’s numerous pores.

In most cases, though, it’s best to choose a device that combines the powers of carbon filtration and HEPA filtration. Such a purifier removes at least 99.97% particles of particles that are > 0.3 microns in diameter.


3. Ionic Purifiers/Ion Generators/Ionizers


Ionic purifiers, also known as ionizers, are some of the quietest purifiers on the planet. That’s because they don’t use fans.

They work by releasing negatively and positively charged particles into contaminated indoor air. Most particles suspended in the air have a neutral charge.

Negatively charged ions bond with positively charged particles including dust. Similarly, positively charged particles bond with negatively charged particles in the air. When that bonding happens, the resulting heavier particle drops to the floor and other surfaces around the house. Vacuuming and dusting should easily take care of the particles at that point.

Particles on the floor and other surfaces won’t bother you unless they get disturbed. But every time you pad across the room, you’ll almost always kick these particles back into the air. For that season, use of ionic purifiers should be combined with regular vacuuming and dusting.

Most ionic purifiers tend to be rather large. And most are pretty affordable. You’ll want to check out a couple ionic air purifier reviews before whipping out that card.


4. Ozone Generators


Ozone generators are portable air purifiers that deliberately produce ozone and push it out to the indoor environment. Manufacturers of these devices say that ozone reacts with pollutants in the room, producing harmless by-products. These harmless byproducts include CO2, O2, and H2O.

But is there such a thing as safe levels of ozone? Well, there’s a body of scientific research that disagrees with that claim. Some studies have shown that chemical reactions involving ozone can result in certain irritating by-products and even odors.

According to the EPA, some of the by-products that manufacturers aren’t mentioning include formic acid and aldehydes. These two compounds can cause irritation in the lungs if a certain threshold is reached. If you’re asthmatic or battle allergies, you’re advised to steer clear of ozone generators.


5. Ultraviolet (UV) Light Room Purifiers


These devices use ultraviolet light to kill bacteria, viruses, and other disease-causing germs. UV light composes three kinds of lights namely UV-A, UV-B, and UV-C.

Earth’s Sun emits mainly UV- A and UV-B light. Now, these rays are known to cause skin cancer and sunburn. Were it not for ozone, the Sun would cause immense suffering on Earth.

But UV-C light is a little different than UV-B and UV-A. The UV-C light that UV light purifiers use destroy pathogens without adversely affecting people’s health.

But do UV light air purifiers work?


If what worries you most are germs and pathogens, UV light air cleaners are probably your best bet. That’s why hospitals and laboratories use the UVC light technology to kill microbes and sanitize spaces.
Note: Only UVC light with wave lengths that are shorter than those of regular UVC light won’t harm people. That’s what a 2017 4-year study found.

The researchers in this study crammed influenza viruses into a chamber and focused 222 nm UVC light on them. They also had another sample that they didn’t expose to UVC light. Then, the scientists obtained liquid samples from each chamber and added them to flu-susceptible dog cells.



The sample exposed to UVC light couldn’t cause infection to the cells. In contrast, the control sample could cause infection to the cells.

Conclusion: UVC light of a certain wavelength is harmless to people.


7 Things to Do Before Buying a Home Air Purifier


Portable air cleaners for home use aren’t exactly cheap. Some air purifiers can be quite pricey (especially the very best ones). I’ve seen models that cost north of $2,500.

If you’re planning to buy one of the more expensive models, you need to read this comprehensive air purifier buying guide first. You’ll avoid lots of air purifier shopping mistakes that clueless or misinformed people keep making.

No one ever wants to spend money on products that aren’t nearly as good as they claim.
And before you whip out your credit card, here are a few things to do.


1. Keep Your Home Sparkling Clean


Marketers of air purifiers may say all kinds of things about their wares. So you must be on your guard. Don’t listen to anyone who says air purifiers are the ONLY solution you’ll ever need for handling air pollution. It’s one of the various solutions you need, not the only one.

Air purifiers don’t eliminate the need to dust or vacuum-clean your home. It’s essential to keep your place sparkling clean all of the time. That should especially be the case if you have asthma or live with someone who battles the condition.

So regularly use HEPA vacuum cleaners to eradicate dust. Also, use a damp piece of cloth or mop to dust different surfaces around your home. The whole idea here is to reduce pollution as much as possible. If you do that, your purifier will have much less work to do.


2. Ensure No One Smokes Indoors


Some air purifiers are known to satisfactorily eliminate tobacco smoke odors. But it’s not a good idea to smoke or let others smoke inside of your home. That’s because tobacco smoke tends to linger for long. Besides, no air purifier can remove every trace of carcinogens released by tobacco smoke.

Researchers have found that there are links between tobacco smoke and certain types of cancer. That’s the reason you shouldn’t take any chances. Ban smoking indoors and save your loved ones from unnecessary exposure to cancer-causing agents.

Why not just use air purifiers to remove tobacco smoke? Yes, they sure help. But in most cases, it’s best to not smoke indoors. Please be patient with me. I’ll very soon show you sound research that answers the question whether purifiers remove tobacco smoke.


3. Maintain Your HVAC System Properly


Having a HVAC system that’s not well-maintained isn’t a good idea. It’s best to have an expert handle the installation process. You also want them to inspect the system from time to time.

What happens if there were mistakes during installation or if maintenance isn’t done right? The system may spew dust and other pollutants back into your home.

Using portable air cleaners in a home that keeps getting pollution from a problematic HVAC system is futile. Before you buy an air purifier, it’s best to have a HVAC system expert come over and give it a look. Once they fix the issues (if any), you can go ahead and order the device you want.


4. Light Candles or Burn Wood Less Often


Everyone needs to use candles or light a wood fire at some point. And that’s ok. Big problem: using candles and lighting wood fires releases pollutants into your indoor air. You can live comfortably without using candles or light wood fire.

Smoke from Burning Wood and Candles Contains …..

….soot (PM=particulate matter), carbon monoxide, and carbon dioxide. Did you know that candle smoke carries carcinogens?

The smoke also carries acid gases, benzene, styrene, metals, dioxins, aldehydes, nitrogen oxides, and PAHs. PAH is an abbreviation for polycyclic aromatic hydrocarbons. It’s not a good idea to inhale any kind of smoke for any length of time.

Smoke causes irritation to the eyes, throat, and nose. Also, it produces smells that may cause nausea. In addition, research has demonstrated that inhaling smoke may interfere with proper lung functioning. So minimize exposure as much as possible.


5. Handle Everyday Products Safely


One recent study revealed a shocking fact. Volatile Chemical Products (VCPs) are a much bigger source of outdoor air pollution than previously thought. In fact, VCPs produce as much if not more air pollution than vehicles.

VCPs include pesticides, paints, vanishes, adhesives, personal care products, cleaning agents, and printing inks.
Of course, VCPs also cause a lot of indoor pollution and you should handle them with care. VCPs contain organic solvents and these solvents produce VOCs (Volatile Organic Compounds).

The study covered 33 industrialized cities in the U.S and Europe. It revealed that volatile chemicals account for 50% of all air pollution!

Now, that’s a scaring statistic.

So be sure to handle these items properly. After use, store them as far away from living areas as possible. Pesticides and insecticides particles are quite small (refer to the table above). For that reason, it’s doubtful that air purifiers can remove them completely. So handle these products with utmost care.


6. Use Cooking Exhaust Hoods


Exhaust hoods help capture and then vent away polluted air emanating from stoves and gas burners. That’s why it’s a must-have item in almost every kitchen.

But kitchen hoods vary so much when it comes to handling air pollution. The least effective hood sees a capture efficiency of as low as 15 percent. By contrast, the best ones see up to 98% efficiency. You should research widely so you can choose the right hood.

I’m really sorry, but this air purifier buying guide won’t discuss about selecting the right kitchen hood. The guide is about helping avoid mistakes while shopping for a portable room purifier.


7. Read Best Air Purifiers Reviews


Pretty much everyone these days reads reviews before forking over the money for a product. You, too, should read honest and accurate air purifier reviews before committing your funds. Suppose you’re looking to address dust in your newly renovated home. In such a case, you’ll want to read the best air purifier for construction dust reviews.

I’ve put together a couple pretty detailed air purifier reviews to help you along the way. I’m very cautious when it comes to making product recommendations. I’ve never recommended and never will (knowingly for personal gain) recommend a horrible product. If it’s terrible, I’ll say it’s terrible.

But this blog isn’t the only place you can read objective purifier reviews. Once ready, you’ll want to head over to Amazon to read customer reviews. When it comes time to do that, be careful. Pay particular attention to negative reviews from real product users.

Also, compare the percentage of negative reviews with that of positive reviews.
A product with 50% positive reviews and 50% adverse ones isn’t probably one you should buy. Generally, a product that receives a star rating of 3.5 and above should be good enough.


8 Important Things to Keep in Mind While Shopping for a Room Purifier


As you browse around for the best deal, there are a couple things to keep in mind. I’ll briefly discuss the most important considerations to pay attention to so you can stay focused throughout the process.


1. Look at Your Needs


Consider your needs. Ask yourself: what do I wish to achieve? Maybe you have asthma or some other bothersome respiratory disease. Or, maybe you’re allergic to dust, pollen, mold spores, or other triggers.

Do you live with lovely pets that also shed? Does the neighbor in the floor below yours smoke all the time? Perhaps you’re 100% healthy but still want to breathe clean, healthy air?

Different air purifiers help people achieve different aims. Once you pinpoint the problem you seek to address, choosing the best portable room purifier should be easy.

If you have asthma, for instance, you definitely need the best air purifier for asthma. To handle tobacco smoke, you should go for the best air purifier for tobacco smoke. And if you’re allergic to pet dander, look for the best air purifier for pets.

Usually, manufacturers indicate the best use to which a buyer can put their device. I bought the Honeywell HPA300 a couple months back. The box clearly says “Allergen Remover,” and that’s why I picked it. We have it in the living room. And thanks to it, my wife (she has asthma) can cook and sleep without problems.


2. The Manufacturer’s Reputation


Just like not all cars are created equal, not all air purifiers are created equal. You should make sure to buy products made by manufacturers best known for excellence. When it comes to air purifiers, the following are some of the companies I’d vouch for:

  • Honeywell
  • Dyson
  • Winix
  • IQAir
  • Coway


A manufacturer known for producing top-notch products is highly likely to continue doing so into the future. While well-known brands can sometimes disappoint, they’ll usually produce goods that satisfy users’ needs.


3. Noise Levels


If your air purifier is too noisy, you’re going to hate it within a week of buying it! Are you a light sleeper? If yes, noise levels should be a critical consideration.

Generally, bigger and more powerful purifiers tend to be noisier than smaller, less powerful options. Also, some brands happen to be noisier than others. In addition, portable room purifiers that use a fan are somewhat noisier than fanless alternatives.

Tip: Buy an air cleaner that’s considerably bigger than the room you seek to purify. If your room measures 250 square feet, for example, you may want choose a device designed to cover larger rooms, say, 300 sq. ft.

A larger machine allows you to use a lower fan speed and still clean the room effectively. And as you know, using a lower fan speed naturally means less noise.


4. How Each Purifier Works


Different air purifiers operate differently. Some air purifiers suck in air via the back and spit it out via the front. You must place such a machine a considerable distance away from the nearest wall. Else, you won’t get maximum benefits from your purifier.

Others such as Dyson Pure Cool, TP04 – HEPA Air Purifier and Tower Fan suck in air from all sides and release it via the top. Still, other purifiers draw in the air from the front and force it out through the top. A good example of such an air purifier is the Honeywell HPA200.

Suppose your room is rather small and the last thing you want is obstruction. In that case, it’d be best to go for a purifier that draws in air via the front and spits it out via the top.


5. Room Size


Room size is another super important consideration. A small room needs a small or relatively large purifier. Similarly, a medium-sized room requires a medium-sized device while a very large room needs a behemoth.

So, before you set out to buy an air purifier, make sure to note down the room’s exact measurements. Measure the space’s width, length, and height. Get the product of all three measurements (cubic feet). Also, calculate the product of W X L (sq. ft).

We’ll see a little further down the road how you’ll use these measurements to pick the best room purifier.


6. Filter Replacement Costs


With some purifiers, replacing filters can turn out to be quite an expensive affair. Generally, the more expensive the purifier, the more expensive the parts. A Purifier that costs north of $2,500 typically uses replacement filters that seem quite pricey.

There are replacement filters on the market that cost hundreds of dollars. Usually, the prefilter is replaceable roughly every three months. Other filters are replaced once or twice a year depending on the room’s extent of contamination.

If the filters turn out to be rather expensive, the costs can really add up over time.
Thankfully, there are certain products on the market that use permanent, removable, and cleanable filters. With such devices, all you need to do is remove the dirty filter or prefilter and clean it. Then, replace the filter and that’s it.


7. Energy Consumption


Air purifiers consume electricity. Upon plugging your air purifier in, you’ll certainly see an uptick in your electric bills. It’s best to buy an Energy Star rated purifier as such a device is normally energy efficient.

Some air purifiers are real monsters when it comes to consuming electric power. One dehumidifier air purifier combo I know (the Pure & Dry HEPA70 (70 Pint) Dehumidifier and Air Purifier – Sealed HEPA Filter ) uses up to 780 watts! Now that’s too much energy. The best air purifier consumes a reasonable amount of power while delivering loads of air filtration.

You can expect to spend between $150 and $250 annually on electric bills and filter replacement. Of course, these are estimates. For that reason, they’re bound to change in the future as filter cost and electric bills increase, as they sometimes do.


8. Budget


Finally, you must address the money question. What’s your budget? First, figure out which brand you want. Next, decide how big the device should be. Finally, make up your mind on how much money you’re ready to spend on the device.

In general, the more expensive, the better the quality. You’d expect a room purifier that costs $1,700 to be of much better quality than one that costs $50.

But that’s not always the case. I’ve seen several relatively inexpensive air purifiers whose performance was incredible. I’ve also seen expensive big-name portable air cleaners that turned out to be huge disappointments for the buyers.

Stick to the Budget


So start with a budget and stick to it. Then, start reading reviews and taking notes. With some determination and a bit of digging around, you should finally find a deal that makes sense.

You won’t make a costly mistake when it shopping for the best air purifier for your needs. No, that won’t happen to someone who’s read arguably the most comprehensive air buying purifier guide on the web.


Portable Room Air Purifiers: Are There Any Benefits?


No one shells out money for a product if they’re not assured of some real benefits. And that leaves us with one big question: do air purifiers deliver any real BENEFITS to users?

Or are they just expensive devices that empty people’s pockets while offering zilch benefits? To answer that question, I’ll rely on available scientific evidence and a little anecdotal evidence.

But before we jump into air purifier benefits, there are a few important facts you should be aware of (if you’re not already). Air pollution has now become “a public health emergency” in the words of the World Health Organization.
Here are 7 shocking facts you should know before you read further.

7 Shocking Air Pollution Facts


1. 40% of early heart disease deaths (in Europe) are traceable to air pollution. That’s according to new research published in the European Heart Journal.

2. Air pollution leads to 14% of early lung cancer and pneumonia deaths in Europe.

3. Air pollution causes 6% of COPD early deaths in Europe every year.

4. Non-communicable diseases such as cancer, lung diseases, and cardiovascular diseases account for majority of deaths in the world. In 2015 alone, NCD led to almost 40 million deaths (71%) according to the European Heart Journal.

5. Toxic air cuts people’s lives short by up to 2.5 years in some cases

6. WHO (2012) reported that 4.2 million people die from breathing toxic air annually. But new research shows that the number has more than doubled. According to the study, air pollution now claims 8.8 million lives globally each year.

7. Breathing polluted air harms people more than smoking does.


Air Pollution, Like HIV/AIDS, Doesn’t Kill People Directly


Now sit and let that sink. Many people argue that air pollution doesn’t kill people, at least not directly. That’s true if you ask me. I like comparing air pollution to HIV/AIDS. Would you say HIV/AIDS kills? The answer, emphatically, is NO.

AIDS kills no one.

But it does seriously weaken the body. It makes it extremely easy for deadly diseases to get in and cause death. That’s exactly how air pollution works. It enters people’s bloodstream and ends up in the brain, lungs, and liver. It has been found that air pollution leads to irreparable damage in these organs.

Now, let us jump in and learn a few air purifier benefits.


7 Air Purifier Benefits You Want to Enjoy


Let’s jump right in.


1. Easier Allergy and Asthma Management


Manufacturers and marketers keep saying that their products help manage asthma and allergic reactions. But do air purifiers help with asthma and allergies?

The straightforward answer is YES, they do. But that’s a difficult question that demands a detailed answer.
I have read credible research that shows that using a several portable room air cleaners does help with allergy and asthma. I’ll refer to three important scientific studies.


Study #1


One of the studies was carried out by Morgan et al. (2004). The study was a randomized control trial. The trial involved an environmental intervention that covered a period of 1 year. It focused on 937 inner-city children, all of whom suffered from atopic asthma.

An assessment for asthma-related complications was performed every 2 months throughout the intervention year. The subjects were also assessed 1 year later.


Atopic Asthma


It is the most common type of asthma on the planet. Up to 90% of children battling asthma are found to have the condition. And 50% of adults who have asthma are specifically dealing with this type. That means the study focused on a form of asthma majority of sufferers endure.


Intervention Used


The researchers had the participants use HEPA air purifiers in their bedroom.




The participants reported seeing appreciably fewer asthma symptoms. They also saw fewer symptoms in the intervention year and even during the follow-up year.

The researchers arrived at the conclusion that using home-based environmental intervention significantly minimized exposure to allergens. In other words, using a HEPA air purifier at home should help asthma and allergy sufferers.


Study #2


Batterman, Godwin, and Jia (2005) conducted a 2-month study that involved tobacco consumers. The researchers conducted both laboratory and field tests to determine whether air purifiers are effective. They performed the field tests in 4 single-family homes over a 2-month duration. The homes had high levels of particulate matter (from tobacco smoke). The researchers used 4-speed HEPA air purifiers.

Several people were instructed to smoke 15-40 cigarettes in each home throughout the period. During the period, the units ran at one of the higher fan speeds. Then, the researchers monitored PM number concentrations, PM mass concentrations, and VOCs levels. Some of the time, they removed the filters. The rest of the time, the machines ran with the HEPA filters inside.




Two things happened. One: PM concentrations in all 4 homes reduced by between 30% – 70%. Two: there was a significant reduction in the half-life of particulate matter ranging between 0.3 and 10 microns in size.

Here’s another significant finding. With extended use, air flow rates for the filters fell by 7-14%. The reason for that was that the prefilters had sucked in some of the particulate matter.

The researchers concluded that air purifiers can appreciably lower PM levels in smokers’ indoor environments. But since performance reduced with filter usage, the smoker needs to keep replacing loaded prefilters.

With that said, you should know that air purifiers don’t work perfectly when it comes to eliminating gaseous pollutants. And while they may reduce tobacco odors, it’s doubtful they’ll completely remove carcinogens from tobacco smoke.


Study #3


Francis et al. (2003) carried out this study. The researchers assessed the effects air purifiers in homes of people who were sensitive to dog and cat allergens.

It was a randomized parallel-group study that involved 30 adults sensitized to and living with cats and dogs. One of the two groups (15 people) used HEPA air purifiers alongside HEPA vacuum cleaners over a 12-month period. The control group (15 people) used only HEPA vacuum cleaners over the same period.




67% of the group that used both HEPA vacuum cleaners and portable air cleaners in their home demonstrated a “beneficial clinical response.” By comparison, only 3/15 or 20% of control group demonstrated a “beneficial clinical response.”
One weakness of this study is that it didn’t allow total exclusion of a placebo effect. The researchers concluded that cat and dog allergy sufferers who use HEPA air cleaners can expect a “small but significant” asthma relief.


2. Make Your Indoor Environment More Livable


We’ve seen that air purifiers reduce indoor air particulate matter. That means using them should make your home feel a lot cleaner, healthier, and more comfortable. But you don’t need to have asthma or be sensitive to pet allergens to use home air cleaners.

Everyone who craves clean air should use home purifiers. Air purifiers are known to effectively handle dust, pollen, mold spores, and dust mites. They also eliminate cooking, tobacco smoke, and other odors to a significant extent. And everyone agrees that a room devoid of air pollutants feels way nicer than one that swarms with them.


3. Using Air Purifiers Reduces the Number of Asthma Visits


One 2011 study assessed the effectiveness of air cleaners in improving asthma symptoms in children exposed to secondhand tobacco smoke. The study involved 225 children aged 6 -12. All of them had asthma. It was a double-blind randomized trial. The children were randomly selected to receive two inactive or active air purifiers. They were then exposed to tobacco smoke (5 or more cigarettes a day over the study’s duration).




The children who consistently used “active” air purifiers saw 42 fewer unscheduled asthma visits. The study, however, found no significant differences in asthma symptoms (parent-reported).

The study concluded that home purifiers should be a part of a “multi-faceted” asthma management strategy. The researchers also insisted that it’s best to ban smoking indoors. Maybe it’s even better to quit smoking altogether.


4. Better Quality Sleep Especially During the Pollen Season


After an action-packed day, everyone desires to enjoy quality sleep when they finally crawl into bed. But allergy and asthma sufferers find it terribly hard to sleep during certain seasons. The allergen season is one such season. Spring pours down life onto Earth, infusing vitality into plants and seeds. But it’s also during this season when allergy and asthma sufferers see the longest, nastiest nights.


Plant Pollen Triggers Allergic Reactions


Spring air contains tons of plant pollen. Some of that pollen ends up inside people’s homes. People with breathing difficulties can’t avoid inhaling pollen from certain grasses, trees, and weeds, and other plants. Maple, pine, pistachio, and oak among others are examples of wind-pollinated trees.


Worse Allergic Reactions


When rain drops fall on pollen, they break them into smaller particles which then end up in asthma sufferers’ lungs. Way more pollen particles get to the lungs than do so during other seasons. And due to their sheer number, allergy season pollen tends to trigger a far worse reaction.


Do Air Purifiers Help with Seasonal Allergies?


Hopefully, a little anecdotal evidence will suffice here. My wife battles seasonal allergies. My son, too. I choose not to detail their struggles with allergy over the years. But they’ve certainly seen improvement in their allergy and asthma symptoms.

Actually, they slept much better the very first night we installed air purifiers in our bedrooms. And they’ve slept much better pretty much every other night ever since. Well, they still visit the doctor. However, it’s clear the purifiers they use deliver observable benefits.


Positive Reviews from Real Users


I’ve read many positive reviews from people who saw near-immediate benefits upon introducing an air cleaner into their room.
But no one should promise you heaven when it comes to having an air purifier around. Still, it’s accurate to say that home air cleaners help with allergy and asthma. That’s why my wife’s pulmonologist advised her to invest in one or two True HEPA air purifiers


5. Avoid Respiratory Diseases


There’s no conclusive evidence that air cleaners help people avoid respiratory diseases. But there’s ample research that links these diseases to air pollution (especially indoor air pollution). Please refer to the 7 shocking air pollution facts stated above.

Earlier, we saw that air purifiers can help remove particulate matter in the range of PM2.5 to PM10. But there are many smaller particles floating around in people’s indoor air. And the smallest particles are deadliest. Unfortunately, even the best portable air cleaners may not remove 100% of ultrafine particles.

Lots of manufacturers say their purifiers eliminate more than 99% of all particles. But the truth is that most great purifiers work best for particles larger than 0.3 microns. Sure, air purifiers also suck PM2.5 out of the air. But they will not do the job as perfectly as they do with PM10.


6. Want to Stay Sharp? Use a Room Air Purifier


Some studies have found significant correlations between considerable exposure to air pollution and cognitive deficits.
Breathing polluted air over a prolonged period can damage the brain and erode its cognitive abilities. In other words, prolonged exposed to air pollution can lead to lower intelligence in humans.

How Inhaling Contaminated Air Affects the Brain


Polluted air affects the unborn, children, and adults. Let’s see how.


• Air Pollution in babies (Unborn) Correlates with Cognitive Deficits


Research has linked prenatal exposure to air pollution to less white matter in children later in life. Scientists have established that pollution inhaled around the third trimester of pregnancy passes on to the baby via the placenta.
Other research finds that small white matter correlates with a slower brain.

Children born of such mothers also tend to have more behavioral problems. That’s not all. Children who start breathing dirty air while still in the womb are more likely to have ADHD.


• Is Your Child Breathing Polluted Air in School?


Researchers in Spain conducted a study that examined the effect of air pollution on cognitive ability. More specifically, the study focused on children exposed to high levels of air pollution emanating from environmental pollution. The children in the research were 3,000 in number and came from 39 different schools.
The study assessed the children’s attention and memory performance once every 3 months over a 12 month period.

Findings after 12 Months


Children whose school saw higher air pollution levels demonstrated less improvement in cognitive performance. The study linked the performance observed with impaired brain connectivity in children exposed to higher levels of environmental pollution.


• Air Pollution on Cognitive Ability in Adults (Recent Study)


Researchers recently examined and analyzed existing data relating to a national survey that had been conducted across China. The survey included different mathematical and verbal ability tests.

All the researchers did was comparing cognitive performance data to daily air pollution numbers from their locality. To get more meaningful information, the researchers excluded county-level variables such as population density and GDP per capita.




The researchers found that areas with high air pollution levels coincided with lower verbal and mathematical performance numbers. They also found that air pollution hit men more profoundly than it did women.

Even more interesting, the effects of pollution were strongest in less educated men! That suggests that inhaling highly contaminated air can make ordinary people dumber! Maybe it’s about time you earned another degree.

These findings are depressing. And that’s where portable home air cleaners come in. These devices (as discussed earlier) remove substantial levels of particulate matter from the air. As a result, the air becomes cleaner and healthier. In the end, a lot less contaminants reach the brain.


7. Lower Medical Bills


Evidence shows that people who use room air cleaning devices may see fewer hospital visits. A systematic review that examined 6.2 million events in 28 countries revealed an interesting finding. The study considered whether higher levels of air pollution led to a higher number of stroke-related complications or fatal health issues.

The findings showed that when the concentration of airborne pollutants was increased, the number of hospital admissions grew significantly. The pollutants examined in the study included CO, NO2, and SO2. Fewer hospital admissions obviously mean lower medical bills over the long term.


But Do You Really Need an Air Purifier?


You do if you have asthma or struggle with allergic reactions. We’ve already discussed about the usefulness of air cleaners for people who battle allergies and asthma. But air purifiers aren’t designed only for people grappling with breathing problems.

Healthy people who understand how dangerous indoor air pollution is should also consider using these devices. There’s no doubt that room air purifiers eradicate harmful particulate matter and even gaseous extents to some extent. For that reason, everyone can and probably should have an air purifier or several of them for home and office use.


General Features of Portable Room Air Cleaners


It’s hard to buy the right product if you don’t know the features you should be looking at while shopping. Before you start the search, you need to understand a few things and pick up a few terms so you can become a smart shopper.

1. Prefilter


Many air purifiers use an additional filter known as a prefilter. If you were to disassemble an air cleaner, this is the filter you’d see first. In most cases, the prefilter is found right after the device’s front cover. Typically, the prefilter is made of activated carbon.


What Particles Does the Prefilter Eliminate?


Activated carbon can and does remove odors and even gaseous particles (to some extent) from polluted air. The prefilter also traps “big enough to be seen with the naked eye” particles from the air. Pet dander, skin flakes, pet hair, human hair, and lint all get filtered out at the prefilter level.

Air purifiers that use a prefilter come highly recommended. Why? Because this component increases the overall effectiveness of an air purifier. In addition, the prefilter makes filtration work a lot easier for the other filter(s).


Prefilter Replacement


For most air cleaners, the prefilter gets replaced every 3 months. But if air pollution levels are high, you may end up replacing it more than thrice a year.

When it comes time to replace the prefilter, make sure to choose the right product. Some consumers buy a carbon sheet and cut it up into smaller pieces which they use as a prefilter. The method certainly saves money. But if you don’t work very well with your hands, it’s best to buy a complete replacement filter pack.


Cleanable and Non-washable Prefilters


Some prefilters can be removed and cleaned. That means you can save money over time if you choose a purifier that uses this type of prefilter. The Winix WAC9500 is an example of an air purifier that uses a washable prefilter.

Many air cleaning devices use a non-washable prefilter, though. With these devices, you need to be a little more careful. Some purifiers (especially the more pricey ones) tend to use prefilters and HEPA filters that are quite expensive.

If you go for a purifier that uses replacement filters that are too expensive, you’ll end up with ever-mounting maintenance bills.

That said, more expensive purifiers and replacement filters tend to be high-quality products that deliver great performance.

But that’s not always the case.

I’ve seen some small (yet powerful) portable air cleaners. Some cost as low as the price of the replacement filters used by some of the more expensive purifiers.

Looking for a purifier that uses a carbon prefilter? You may want to read this Honeywell HPA300 review or Honeywell HPA200 review. You may also check out this Dyson Pure Cool TP04 review. Or even this Winix WAC9500 review.


2. True HEPA filter


The True HEPA filter is a component designed to remove 99.97% of particulate matter bigger than 0.3 microns. HEPA is an acronym for High Efficiency Particulate Air. HEPA also means High Efficiency Particulate Absorbing or High-Efficiency particulate Arrestance.

It’s a kind of mechanical air filtration component that forces air via a fine mesh. It’s pretty much like a mat made of fiberglass fibers that are randomly connected to each other.


Particles Removed by True HEPA Filters


As the air passes through the mesh, fine and ultrafine particles get picked up. Some of the particles eliminated include pollen, tobacco smoke, dust mites, pet dander, pollen, mold spores, VOCs, and more.


True HEPA Standard


There’s a reason HEPA filters are so popular even though some are quite expensive. It’s because they work. It’s because True HEPA filters meet certain set standards.

According to the European standard, HEPA filter must have the ability to filter out not less than 99.95% of particles bigger than 0.3 microns.

In the U.S., HEPA filters must demonstrate ability to remove not less than 99.97% of air pollutants larger than 0.3 microns. The True HEPA standard came into existence in the 1940s. That’s after the Atomic Energy Commission had developed the soon-to-be famous HEPA filters.


HEPA Filters are Quite Versatile


Due to their super high efficiency, HEPA filters are used in various medical devices and semiconductors. They’re also used in nuclear products, vacuum cleaners, vehicles, and many other applications.

HEPA filters are also widely used in isolation wards in hospitals and surgical theaters. Why would smart people such as physicians and surgeons use devices that don’t work?

These devices are also used in pharmaceutical processing, bioengineering and other situations that require elimination of tiny particles.

So take care while shopping so you won’t get ripped off. Some manufacturers use low-quality HEPA filters that don’t do users much good. If you purchase a purifier that uses pseudo filter (s), you most likely won’t like the results you get.


History of True HEPA Air Filters


HEPA filters came onto the scene during World WAR II. The War ended in 1945. Yes, these filters are that old. Unless you’re a history buff, you likely thought HEPA filters are a pretty recent invention.


The Atomic Energy Commission Invented HEPA Filters


Who invented HEPA air filters? It’s the Atomic Energy Commission. Purpose? The AEC developed this filter to help filter out radio-active particulates. To produce HEPA filters, scientists from the U.K., Canada, and the U.S. joined forces and executed the Manhattan Project.

The Manhattan Project was designed to help find a way to handle radioactive dust and other particulates. The project not only discovered the first ever HEPA filter but also the first-ever atomic bomb.

Made to Protect Scientists from Radioactive Radiation


Why did the Commission need to filter out atomic particulates? It’s because they needed to protect the scientists from harmful radioactive exposure. If HEPA filters protected scientists from radioactive exposure, surely they can handle many less dangerous particulates. You now know why everyone recommends HEPA filters.


Stop Worrying about Radiation from Japan


Do you ever worry about radiation from Japan reaching the U.S. and causing untold devastation? Stop worrying. The U.S. Nuclear Regulation Commission assures everyone that no harmful radiation levels will ever reach America. Also, the EPA strives to monitor, collect, and share radiation data daily through RadNet.


Difference between HEPA Filters and Standard Filters


The main difference between these two kinds of air filters is that HEPA filters are way more efficient than standard filters.

But why are HEPA filters more efficient?

HEPA filters are a kind of extended surface filters. The EPA calls such filters “pleated” filters. “Pleated” means that these filters have an increased surface area for air filtration.

Thanks to the increased surface area, these pleated filters allow the manufacturer to significantly increase the filter’s packing density.

By contrast, standard air filters aren’t pleated. They’re often referred to as panel or flat air filters. Naturally, flat filters have a smaller surface area. As a result, the manufacturer can’t pack as much fiber there. It’s best to choose a home air purifier that uses True HEPA (pleated) filters.


HEPA vs HEPA-like or HEPA-type Filters


Either a filter is HEPA or NOT HEPA, period. There’s nothing like HEPA-like or HEPA type. When shopping for the best air purifier, keep in mind that some air purifier marketers out there are hawking non-HEPA filters as though they were HEPA.

Don’t be taken in, they’re selling low-quality products passing them off as high-quality, well-known ones. IF IT’S NOT TRUE HEPA, it’s not going to get rid of 99.97% of contaminants from your indoor air. That’s because it doesn’t meet the U.S. HEPA standard.


3. Handles


If you have one air purifier, you may need to move the device quite often. For that reason, it’s best to pick a purifier that has handles. Some air purifying devices don’t feature carrying handles.

Handles are particularly important if the machine you want to buy is relatively heavy or bulky. Take the Dyson Pure Cool TP04 air purifier, for example. The device comes with a tall loop that also seems like the best way to carry the device.

However, Dyson says to not carry the device by the loop. If the carrying handle was the most important thing for you, you would probably buy something else. Maybe you’d buy the Honeywell HPA200 instead. It has two handles, each on either side for portability. Thankfully, the Dyson TP04 is quite light and the issue of handles shouldn’t be such a big deal.


4. Fan and Fan Speed


Most air purifier use a fan to suck in dirty air. But some don’t, and these devices tend to be relatively quieter. The downside is that such machines aren’t as efficient as those that use a fan.

Every device comes with clearly indicated speed settings. Many products feature four fan speeds while others like Dyson purifiers feature up to 10 fan speeds. But you’ll find that speed 6 of a speed 10 purifier corresponds to speed 3 of a 4-speed fan machine.

You really shouldn’t worry about fan speeds, though. And the number of speed settings shouldn’t determine what you buy.

Only two things matter: How noisy is the device? How efficient and powerful is the machine at low, medium, high, or turbo speed? Consider this: the Honeywell True HEPA Allergen Remover, 465 sq. Ft, HPA300 on Turbo is considerably noisier than the Dyson TP04 speed 10.


5. Auto Shutoff Timer


Most modern air purifiers come with an auto shutoff timer. But some products don’t have this feature. The Honeywell HPA090 is a case in point. The feature lets you leave your device running for a pre-determined number of hours.

When the selected shutoff time arrives, your machine automatically shuts off. That’s a cool capability for when you need to step out for a couple hours. You need to breathe clean air when you come back.

Many products will let you choose 2 hours, 4 hours, and 8 hours. Others allow you to select 1, 4, and 8 hours.
Frankly, I’ve not managed to figure out why these machines don’t offer more shutoff timing options. Still, I don’t think any user would be seriously inconvenienced because they couldn’t choose 3 or 5 hours.


6. Filter-change Indicator


Many air purifiers feature an electronic filter-replacement indicator. The indicator is designed to remind the user to prepare for filter replacement.

Normally, the light comes on before the filter or prefilter has been 100% used up. Typically, there are 2 separate indicators. One indicator for the prefilter and the other for the HEPA filter.


7. Remote Control


Not all devices come with a manual remote control. Modern devices can be operated using touch buttons or a smartphone application.

I’d go for an air cleaning device that supports remote control, control via an electronic panel, and smartphone control. With such a device, you’d not worry if one of the control functionalities stopped working.


8. Air Quality Indicator


Some air purifiers can sense the level of air pollution in a room. To know how bad indoor air pollution is at any time, you simply glance at the display.

Such devices display air quality data via an LED display. These air cleaners automatically get into purification gear immediately they sense air pollution in the room.

In most cases, leaving your device in auto mode is the best option. The machine is designed to self-regulate and take appropriate action depending on current air quality levels. I’d say Dyson produces some of the greatest purifiers regarding the ability to sense a room’s air pollution levels.


9. Wheels


Certain heavier models come with wheels. Wheels make moving your air purifier hassle-free.

10. Crave Convenience?


Many purifiers these days allow users to link to smartphone apps. Such devices are typically Wi-Fi and Bluetooth enabled. Once you connect the device to the app over Wi-Fi, you can control your device from across the room without touching the remote control. Apps are cool for when you have mobility challenges or when you’re feeling lazy.

If your air cleaning machine features an air quality indicator, the app enables you to access the data instantly. The Dyson Pure Cool TP04 generates instant and accurate air pollution reports.


11. Alexa Enabled


Now not every air purifier is Amazon Alexa-enabled. But if you’d like to own such a device, you have options. Such a device lets you talk to it. You can turn it on, off, adjust fan speed, and so on.

But in most cases, there’s a thing or two you can’t do via voice commands. The Dyson Pure Cool, TP04 – HEPA Air Purifier and Tower Fan is a great example of an Alexa-enabled purifier.


4 Important Air Purifier Numbers to Understand


In this section, we’ll look at 4 important numbers namely CFM, CADR, ACH/ACPH, and purification coverage.




ACH is means Air Changes Per Hour. The number indicates the number of times an air cleaning device circulates air in a room with defined measurements.

Suppose a purifier on the highest fan speed circulates air 5 times in an hour. Further, assume the testing room’s measurement coincides with the device’s stated purification coverage, say, 250 sq. ft. In that case, the device’s ACH is 5.

People who have asthma and those who experience allergic reactions should pick a purifier with an ACH of 4 or higher. That also seems to be a good number to go with even for people without breathing problems.

Some devices don’t indicate ACH, though. I’m not saying don’t buy such products. Instead, I’m saying it’s a nice thing to know the ACH of your device.

Note: the ACH isn’t exactly a fixed number. If you move your purifier to a smaller room and run it on the same setting, the ACH will increase substantially. A purifier with an ACH of 5 may demonstrate an ACH of 7 in a smaller room. The same purifier would demonstrate a lower ACH if you moved it to a larger room. Hope that’s clear.

A little further down the road, I’ll show you how to estimate the ACH of an air purifier. I’ll show you how to estimate it using your room’s volume number and the device’s CFM.


2. CFM


CFM is another measure of a purifier’s efficiency. Manufacturers usually indicate this number on the products they make. CFM means cubic feet per minute. It measures how much air in cubic feet a device purifies every passing minute. CFM is a description of the volume of air that passes through a device at a certain point. During testing, this number is recorded at the point the air leaves the unit.

How to Calculate How Much CFM Your Purifier Should Have


Simply multiply your room’s volume by the ACH you need. Finally, divide the result by 60. An example will make it crystal clear for you.

Assume your room measures (10 X 12 X 8) feet. Let’s also say you need an ACH of 5. How much CFM do you need?

(10 x 12 x 8) x 5
= 80. You should buy an air purifier whose CFM is 80.


Determining Maximum Room Size Using CFM and ACH


Let’s assume you’ve decided that the ACH you need is 5. And that you’ve come across this great room air cleaner that has a CFM of 400. With these two numbers, you can accurately calculate the largest possible room that device can effectively clean.

Here’s the formula:

(CFM X 60)/8
Desire ACH

Let’s do the math now:

(200 X 60) /8

=300 sq. ft.

That air purifier shouldn’t be used to clean a room a square inch larger than 300 sq. ft.


How to Estimate/Calculate the ACH of an Air Purifier Using CFM


Engineers and air purification experts rate air purifiers by volume of air they can move in one minute. If you an air purifier’s CFM and your room’s volume (L x W x H), you can estimate an air purifier’s ACH.

Steps to follow


First, get the product of your room’s length, width, and height. For example: (10 x 12 x 8) feet which gives us a volume of 960 cubic feet.

Next, check the product’s manual for its CFM. Let’s say the CFM is 150. That is, it moves 180 cubic feet of air per minute.

Then, multiply the CFM by 60. Multiplying by 60 converts cubic feet per minute (CFM) to cubic feet per hour. In our example, we’d get (150 x 60) 9,000 cubic feet per hour.

Finally, divide the device’s cubic feet per hour by your room’s estimated volume.
In our example, we get an ACH of 9 (9,000/960)


2. Purification Coverage


Every device is designed to clean rooms whose measurements don’t exceed a certain limit. Normally, manufacturers indicate each device’s purification coverage. This number gives you a pretty straightforward estimate as to the room size it’s best for.

Here’s something you should do before starting the search for that perfect air cleaning solution. Take the measurements of each room you wish to purify.

Let’s say you’re looking to buy a purifier for a standard size bedroom: (10 X 12) feet. Do this: work out the product of those two numbers.

The result is 120 sq. ft. That number should help you quickly choose the right size. In this case, it’s best to pick a purifier designed to clean rooms larger than yours by a significant margin.

A home purifier made for a 150 sq. ft. room would be a great bet here. If you love Honeywell products like yours truly, you’d pick the Honeywell HPA100 155 sq. ft. allergen remover.


CADR: Clean Air Delivery Rate


Developed by AHAM, CADR helps consumers compare purifiers in terms of how fast they can eliminate 3 types of particles. The particles are smoke, pollen, and dust.

AHAM is an acronym for Association of Home Appliance Manufacturers. The numbers correspond to an air purifier’s performance in a standard room (one that measures 1,008 sq. ft.). That’s roughly 10 X 12 X 8 feet, or about the size of a standard American bedroom.


How to Calculate CADR Using AHAM’s Rule


I’ll show you a smart way to calculate the CADR you need on your purifier. Using your room’s square footage, you can estimate the CADR your device should have.

AHAM recommends that consumers follow what they call the 2/3 rule.

Here’s the rule: the best air purifier for your room should have a CADR that’s at least 2/3 your room’s square footage.

Let’s say your room measures (15 X 12) feet or 180 sq. ft. What’s 2/3 of 180? It’s 120. The best device for your space should have a CADR that’s slightly bigger than 120. And that’s pretty straightforward.


Using CADR to Determine Correct Room Size


You’re reading a detailed review for the Honeywell HPA300. You noted that the device’s CADR for smoke is 300. But at the moment you don’t have your room’s measurements.

So how can you determine the perfect room size that air cleaning product would work best for?

Here’s the formula:


1.55 X the CADR for smoke.


In this example, you would get: 1.55 X 300 (CADR) = 465 sq. ft.


AHAM’s CADR Ratings


In most cases, AHAM provides 3 CADR numbers. There’s a CADR number for smoke, pollen, and dust in that order. AHAM starts with the smallest particles which also pose the highest risk to people. That’s why they start with smoke, then pollen, and finally dust.


Manufacturers submit their Products Voluntarily


Manufacturers sign up (voluntarily) and become AHAM members so they can use the organization’s testing services. But some companies choose not to become paid up members of AHAM for various reasons. I know at least one company (Dyson) that doesn’t pass on their purifiers to AHAM for testing. As a result, Dyson doesn’t include CADR numbers in their products’ specs.

Thankfully, Dyson’s engineers subject the company’s product to the most rigorous tests you could imagine. Maybe that’s why they keep explaining why the CADR number isn’t important. I strongly feel they should start availing this information, though. Please don’t count that against Dyson. In fact, the company produces some of the most powerful, effective, beautiful, and smartest purifiers on the planet.


Certifications Relating to Room Purifiers


Every device that has been independently tested by AHAM carries the organization’s seal on its box. While researching for your air purification needs, be sure to check out product specifications. Most air purifier reviewers and experts almost always state whether a device is AHAM certified.


Energy Star Rating


Energy Star rating is another certification you need to keep an eye on. Generally, purifiers that are Energy Star certified use considerably less energy than those without this certification. You want a high-performance room air cleaner that’s also a great energy saver. So, always check whether the device you’re interested in is Energy Star rated.


Which is the Best Air Purifier for Me?


The best air purifier for you is one that satisfies majority of your needs. If you’re asthmatic, the purifier should use True HEPA filters. Meaning any purifier that uses other kinds of filters gets eliminated. Also, you should go with an air purifier designed for a slightly bigger space than your room.

In addition, you should follow AHAM’s 2/3 rule.

Have asthma?

Don’t buy an ionizer. You see, choosing the right air purifier for your home is pretty easy.
At this point, you should head over to the air purifier reviews section on this website. Read a couple reviews and see how you feel.

I’m sure you’ll find a great deal that aligns with your budget and specific air purification needs. Alternatively, you can also head over to Amazon and read customer reviews there.


A Comprehensive Air Purifier Buying Guide: Final Thoughts


This comprehensive portable room air cleaner buying guide should help you sidestep common shopping mistakes. Whether you’re an asthma or allergy sufferer or are just looking to purify your indoor air, this detailed shopping guide got you covered.

It covers (hopefully) everything you’d ever want to know about room air pollution control devices. Want to look around a bit and read a few detailed air purifier reviews? That’s a good idea. Here are a couple reviews to start you off:

Honeywell HPA300 review

Dyson Pure Cool TP04 review

Honeywell HPA200 review

Winix WAC9500 review

Honeywell HPA300 vs Honeywell HPA200 vs Honeywell HPA100

Air Purifier vs Dehumidifier vs Air Purifier dehumidifier combo


You may also want to head over to Amazon right now and check out a few products. Check out the Honeywell HPA100 True HEPA Allergen Remover 155 sq. ft. and then explore the site to see if you’d like something else.


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