Welcome to Indoor Air Guides. We are here to provide resources so that you can be well informed in finding the best air purifier for your needs and improving the air quality in your home.


If you new to air purifiers or just need a refresher then this short introduction below will help you.

Visit our About Air Purifiers section or How Air Purifiers Can Help section above to learn more about the how air purifiers can be a benefit in your home.

What is an Air Purifier?

An indoor air purifier is a machine that’s been designed to eliminate harmful particles, allergens and toxins from the air. Create a better home environment by having an air purifier to freshen the air around you.

To determine which kind of air purifier you buy, you must first figure out what particles you want to get rid of in your home air.

Examples of this include dust, pollen, mold, fungi, pet dander, smoke, volatile organic compounds, odor, viruses and bacteria.

Take a look at our section on what air purifiers can do to find out which air purifiers will suit your needs.

Key Features to Look for

When you’re comparing two or more air purifying devices there are really only a few key features you should focus on. Everything else is just marketing hype.

Air Filtering Types

Every air purifier is designed to work best with with a specific type of filter that is manufactured to remove certain particles.

Air purifiers may feature only one type of filter or they may contain a combination of two or more. When you are choosing an air purifier for your home, it’s important for you to know which kind of particles each filter is best at removing. Then, you’ll know which air purifier is best suited for your specific needs.

Hepa Filter

HEPA stands for High Efficiency Particulate Air. This type of filter is rated to capture 99.97% of harmful particles from the air. For this reason, it’s the most highly recommended type of air filter by doctors and allergists. It gets rid of most allergens and dust particles that cause breathing problems.

UV Light Filter

An Ultraviolet light filter kills harmful bacteria, viruses and other pathogens that make you sick.


Activated Carbon Filter

An Activated Carbon Filter is the only filter that removes particles from the air that cause smells and odors. It is highly efficient at eliminating odors created by chemicals, volatile organic compounds, mold, smoke, gases, paints, pets and cooking.


Ionizers work by sending out negatively charged ions into the air that attach to positively charged particles like dust and other allergens. The bonded particles become very heavy, fall to the floor and don’t enter into your lungs when breathing. You still must vacuum regularly to get ride of these particles.

CADR Rating

CADR Rating

The CADR rating is the most important specification when it comes to air purifiers. It tells how well the product actually cleans the air.

CADR stands for Clean Air Delivery Rate. This rating is calculated by the Association of Home Appliance Manufacturers (AHAM) and it stamps its certification only on those products that meet a specific criteria.

What you’ll find on these types of devices is a scientifically backed set of numbers that tells you exactly how effective an air purifying product is against removing dust, pollen and tobacco smoke.

ACH Rating

ACH Rating

The ACH rating stands for Air Changes Per Hour Rating. This rating tells you how often the air is filtered each hour by the air purifier.

For example, an ACH rating of 5x means that the air is filtered 5 times per hour. The higher the number, the better the product operates.

Maximum Space Coverage

Every air purifying product is designed to purify a space up to a certain amount of square footage. This number is important to consider based on your room size. Choose the correct air purifier that efficiently serves your room.

Energy Star Certification

Energy Star Certification

The energy star certification is important as it helps you pick a device that efficiently runs so that you don’t waste your money on your energy bill.

We hope that our guide above was helpful for you to quickly understand what is the best air purifier features to look for when comparing products.

If you want to find out how to fix a specific problem inside your home, such as pet dander, pollen, smoke and allergies then check out the How Air Purifiers Can Help section.

If you’re ready to move on and start reading ratings and reviews for air purifiers, then jump over to our Product Reviews section. There we’ll show you the top devices on the market and help you find the best air purifier for your home.


About Air Purifiers

Find out everything there is to know about air purifiers, including what they do, how they operate, how they can help and the benefits they provide for your health. You’ll discover that not all air purifiers are designed to clean the air in the same way and a device that may be good for one situation might not be right for another. You’ll also find out what the best home air purifier is for specific indoor conditions.

Useful articles include:

Air Purifier Reviews

In our product reviews section, we evaluate the best air purifiers on the market and show you the pros and cons of each air purifier. We also have many buyer guides to help you choose the best device for your home.

Helpful Buyers Guides include:


We’ve researched and reviewed the top 10 best air purifiers for 2020. Here’s a handy comparison table that shows the most important specs and features for each of the top air cleaners.

PhotoNameFilter TypeRoom CoverageCADR Rating (cfm)ACH RatingRatingReview
Rabbit Air MinusA2Pre-filter, Medium filter, BioGS HEPA, Customized filter, Activated Carbon, Ionizer700 square feet166 Smoke | 173 Dust | 171 Pollen2X ACH⭐️⭐️⭐️⭐️⭐️Read More
Germ Guardian AC4100True HEPA, Activated Carbon, UV-C Light100 square feet50 Smoke| 66 Dust | 76 Pollen2X ACH⭐️⭐️⭐️⭐️Read More
Honeywell HPA300 True Allergen RemoverTrue HEPA, Activated Carbon465 square feet300 Smoke | 320 Dust | 300 Pollen5X ACH⭐️⭐️⭐️⭐️⭐️Read More
Winix PlasmaWave 5500-2True HEPA, Activated Carbon, PlasmaWave360 square feet232 Smoke | 243 Dust | 246 Pollen4X ACH⭐️⭐️⭐️⭐️⭐️Read More
Coway AIRMEGA 300S2 Pre-filter, True HEPA, Activated Carbon Filter1256 square feet260 Smoke | 260 Dust | 260 Pollen2X ACH⭐️⭐️⭐️⭐️⭐️Read More
Hamilton Beach True Compact Pet Air PurifierHEPA-type, Activated Carbon140 square feet35 Smoke | 35 Dust | 35 Pollen2X ACH⭐️⭐️⭐️⭐️Read More
Winix HR900 Ultimate PetPet pre-filter, mesh pre-filter, True HEPA, Activated Carbon, PlasmaWave300 square feet194 Smoke | 200 Dust | 220 Pollen4X ACH⭐️⭐️⭐️⭐️⭐️Read More
Coway Mighty Air (AP-1512HH)Pre-filter, True HEPA, Activated Carbon, Ionizer361 square feet233 Smoke | 246 Dust | 240 Pollen4X ACH⭐️⭐️⭐️⭐️⭐️Read More
Holmes HAP242-NUC Air PurifierHEPA-type, Ionizer109 square feet72 Smoke | 72 Dust | 72 Pollen2X ACH⭐️⭐️⭐️⭐️Read More
Levoit Core 300Pre-filter, True HEPA filter, Activated Carbon Filter215 square feet145 Smoke | 140 Dust | 141 Pollen5X ACH⭐️⭐️⭐️⭐️⭐️Read More


According to the U.S. Environmental Protection Agency, indoor air quality is 2-5x worse than the outside.

Importance of Indoor Air Quality

“Indoor air quality” refers to the quality of the air in your home, school or office. The potential impact of indoor air quality on human health is due to several factors:

  • Americans spend about 90% of their time indoors.
  • People who are most vulnerable (young, elderly, immune supressed) to the effects of pollutants spend even more time indoors
  • Indoor contaminants have increased due to new building materials, furniture, personal care products, pesticides and chemical cleaners

The outbreak of the Coronavirus have forced people to stay indoors to flatten the curve of the infection. Since we are all spending more time at home than ever before, we must improve our indoor air quality.

For further information on indoor air quality sources and pollutants, check out our guide on air quality.