How to Buy Air Purifiers

What YOU Should Know Before YOU go Shopping!

Before trying to buy air purifiers, please read this guide. We have created this air purifier buying guide to help you choose the best air purifier to meet your needs.

Unfortunately, there is no "one size fits all" air purifier. When shopping for an air purifier there are many things to consider. Hopefully, this guide will help you evaluate different models of purifiers. We want you to pick the one that best suits your needs.

Before trying to buy air purifiers, be sure to read all of this guide. Follow the links to other pages to find out more detailed information about each topic.

To find what you are looking for quickly, use the table of contents.

Table of Contents

Reason for Getting an Air Purifier

This is probably the most important consideration most people before you try to buy air purifiers. Ask yourself why you want or need an purifier. Do you have allergies, asthma, MCS, other respiratory problem. Do you just want clean air?

Whatever your reason, you need to define it now. Keep it in mind as you shop. This will force you to focus on finding the correct air purifier.

That being said, here are some common reasons and types of filters we recommend.


This is the most common reason to buy air purifiers. Three of the most common allergies are pollen, pet dander, and dust mite residue. All of these are particles in the air. You need a filter capable of removing them from the air. For more information read Air Purifiers, Asthma, and Allergies.

Filter Type




In order to help asthma suffers a purifier has to remove asthma triggers. These triggers can be both particulate and gaseous. When you go shopping to buy air purifiers to help your asthma be sure it can remove both of these.

Filter Type

HEPA and Activated Carbon



The purifier needs to be able to remove odors, gases, chemicals, and VOCs. It also should not produce by-products. Check to ensure the paint and parts don't off gas and produce even more chemicals.

Filter Type

Activated Carbon with Alumina, Zeolite, or Potassium



For people wanting cleaner, fresher air and there are no overriding health issues.

Filter Type

HEPA with Activated Carbon

Type of Air Pollution

There are many things that affect indoor air quality. Air purifiers are designed to remove air pollution from the air. Before trying to buy air purifiers, take a minute to examine what you are trying to remove.

Airborne Particles

These particles include pet dander, pollen, dust, dust mist residue, and mold. These particles typically range in size from 0.2 to several hundred microns. HEPA filters are the best at removing particles from the air.


These include anything you can smell ranging from cooking smells to cat litter box smells. For the best odor removal, use an activated carbon filter.

Chemicals and Gases

These are smoke, VOCs, and other chemicals. VOCs are chemicals like formaldehyde, chlorine, and benezene. They are given off by many common household items: paints, glues, cleaning supplies, new carpet, air fresheners, and many others.

Type of Filters

There are several types of filters available for air purifiers. After you know what you need to remove from the air, you can find the best filter to use before you go shopping to buy air purifiers..

We cover 7 different types of filters.

  • HEPA
  • Activated Carbon
  • Negative Ion Generators
  • Ionizers
  • Electrostatic Precipitators
  • UV Light
  • Ozone Generators

You can read about each of these filters here at Air Filter Reviews.


Before going to buy air purifiers you need to know how much each air purifier cost. Don't rely on just the sticker price. Each air purifier is built differently and becuase of this each will have different operating cost.

When considering and comparing air cleaners, keep three cost in mind.

  1. The cost of the actual purifier. This can vary from a couple hundred dollars to over a thousand bucks.
  2. The cost to maintain the purifier. This is the cost of replacement filters, cleaners, and time.
  3. The cost of electricity. Most purifiers are very energy efficient, but you should check, just in case.

Read more about air purifier cost here before you go to buy air purifiers. We take you through each factor and explain how to ensure you won't have any surprises when you get home.


There are two sizes to check. The first is the size of the machine. Make sure that it will fit in the space you have available. Please don't buy a big purifier if you have a small room. They can range in size from small enough for a desktop to a couple of feet across.

Also think about the weight of the machine. They can range from a few pounds all the way up to 50 pounds. If you plan to move the purifier around everyday, make sure you get a light on. Not many people want to pick up a 50 pound several times a day. If you do get a heavier machine, check to see if it comes with caster (wheels). Most of them do. Some of them charge extra for the wheels.

The second consideration before you try to buy air purifiers is the size of the room. They are not meant to clean the air in your whole house. They work best in one room. As you move farther away from the machine, the efficiency decreases. We recommend that you place your air purifier about 10 feet away from where you spend most of your time.

Every company puts the recommended room size one the box or in the manual. Be sure to check the recommended room size before you buy an air purifier. However, don't take these numbers at face value. There is more to it than meets the eye. You need to do a little checking first.

It is important to figure out the number of air exchanges per hour the air purifier will provide. We recommend that you have at least 6 exchanges. How do you find out how many exchanges there are? Read about air exchanges here. It will tell you how to find the number of times as air purifier will change the air.

Be sure to read this before YOU buy air purifiers or YOU may be wasting your money.


Air purifiers will make noise. Every air purifiers that uses a fan, that is. The amount of noise will be different in each air purifier. The design will affect the noise levels. Some are very noisy, while some are extremely quiet. Some are even marketed as providing "white noise." White noise can help some people sleep and keep others awake.

Most air cleaners have multiple fan speeds. On low speed they will be quiet, but their performance will decrease. On high speed they will clean more air, but they are also much louder. Some machines are programmable. You can turn it off and set it to turn back on after you go to sleep.

It makes sense to leave the air purifier on its lowest setting while you are in the room. When you leave the room, you can turn it on high for a burst of cleaning.

Unfortunately, there is no way to really know how loud an air purifier is until you use it. If you are buying from a store, ask to turn it on. This will let you know how loud it is going to be. Some manufactures list the noise level on the box. They will tell you how many decibels (dB)the machine produces. Our experience is that these are a good guideline, but be aware that sometimes the actual noise is a little louder than what they claim. When you are trying to buy air purifiers, really consider the level of noise it will produce.

To help you figure out how loud an air purifier is you can use this noise chart. Find how many decibels the purifier produces and you can compare it to some common household appliances.



Phone Ringer




Garbage Disposal




Hair Dryer


Moderate Rainfall




Washing Machine


Lawn Mower




Leaf Blower






CADR Ratings

When trying to buy air purifiers, another thing to check is the CADR ratings. The Association of Home Appliance Manufacturers (AHAM) rates air purifiers. It give the a Clean Air Delivery Rate (CADR). This is a way to measure how efficient an air purifier is. Each purifier is tested on how well it removes three pollutants:

  1. Tobacco smoke (smallest particle size)
  2. Pollen (medium particle size)
  3. Dust (Large particle size)

The higher these numbers are the better the air purifier will clean the air. CADR ratings are recognized by both the EPA and the American Lung Association.

That being said, CADR ratings are not perfect. There are several problems with the testing system AHAM has developed.

  1. It only checks for the removal of particles not gasses.

  2. It only test particles 0.1 microns in size and larger. Removal of the smallest particles is the most important.

  3. It only last about 3 days. This is not enough time to check for long term filtration.

Many manufacturers of very high quality air purifiers do not submit them for testing. For now, AHAM testing is voluntary. It can be difficult to compare purifiers if one of them has not been tested.

CADR ratings should not be the reason to buy or not to buy an air purifier. They are far from perfect. When you want to buy air purifiers , we recommend using them as a rough guidline only. If you are trying to decide between two equal purifiers, then pick the one with the higher CADR number.


Almost every purifier comes with a warranty. If it doesn't have a warranty, you shouldn't buy it. The length of the warranty and what's covered varies. For most their warranty last between 1 - 3 years. Usually, the more expensive the air purifier, the longer the warranty period.

Generally, the warranty covers the motor, electronics, and workmanship. They don't cover filters. There are two companies that have great warranties.

  1. Alen Air offers a lifetime warranty. If anything happens to the motor or electronics, Alen will repair or replace your machine. Filters are not covered.

  2. Austin Air offers a 5 year warranty on parts and labor. They also offer a 5 year warranty on their filters. They offer a prorated discount on new filters, if the filter doesn't last a full 5 years. To the best of our knowledge no other company offers a warranty on their HEPA filters.

Be sure to read the warranty. Some commons things that will void it are:

  • Using unauthorized repairmen
  • Using unauthorized parts
  • Repairing the machine yourself/li>

Find out what is required before you go to buy air purifiers. Sometimes you will have to replace the filters every 6 months, whether they need it or not. This can really cause maintenance cost to increase.

Also be aware of who pays the shipping cost. Most of the time, the customer will have to pay shipping back to the company for repairs. If the machine weighs 40 - 50 pound, this can really add up.

Another hidden cost to watch out for is a "handling" charge. The company will charge you a fee any time you return a purifier. We think this is kind of ridiculous. We think if the purifier has a problem you should not be charged when you return it. KAZ, the distributors for Honeywell, do this. They will charge you about $15 if you return a broken machine.

The main point is to throughly read the warranty. If you have any questions about it, ask them. Don't assume every warranty is the same. Don't wait until after you buy a purifier to find out what is covered under warranty.


Another thing to check before you buy air purifiers, is if the purifier gives off any unwanted by-products. The big one here to look out for is ozone. We are not going to debate the benefits of ozone. Ozone is harmful to humans and animals if too much is breathed in. You do not have to worry about ozone with a HEPA filter. Ozone can be produced by electronic air purifiers. If the purifier has an ionizer, it could give off ozone.

Several years ago, many ionzers, or filterless, purifiers gave off ozone. In the past couple of years, manufacturers have gotten better making purifiers that do not emit ozone. Check with the manufacturer to see if the purifier is certified to be ozone free.

If you have multiple chemical sensitivities (MCS), check to see if the machine has any other by-products. Watch out for paints, motors, and plastics that off-gas. This could make you condition worse. Look for an air purifier specially designed for people with MCS. Aireox air purifiers are great for people with MCS.

Special Features

This is the last thing to consider before you buy Air purifiers can have many special features. We put these last becuase these are not the most important features of an air purifier. These are the extras. You do not need these to get good, clean air. These are for your convienence.

Air purifiers range from single speed with an on / off switch all the way to fully loaded models. You can find purifiers with detachable control panels, automatic pollution sensors, automatic fan control, and remote controls.

Here are some special features:

  • wheels or casters
  • remote control
  • digital controls
  • mulitple fan speeds
  • handles
  • timers
  • filter change indicator light (we think this should be a standard feature)
  • automatic pollution sensor
  • automatic fan

There are more special features available. The more features you get, the more expensive the purifier will be. Decide which features you really need and want.


Follow this guide and you will be sure that you get the air purifier you really need.

If you have any questions we are here for you. Just drop us a line and we will do our best to answer any questions you have. Don't try to buy air purifiers until you understand what you are getting.

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