Best Air Purifier Buying Guide | What To Know

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Buying an air purifier? There is important information to know to help you select the best one for your needs such as the filter type and noise level. This article will provide what you need to know about air purifiers.

Learn about the differences in filtration, noise levels, and effectiveness of air purifiers in this buying guide. These tips will help you purchase the right purifier for you.

And if you want to learn some other skills such as how to fix issues with an instant pot, or looking to buy a water filter, or wondering if a Dyson Fan is worth it, I’ve got you covered with my other articles.

Tips To Buy An Air Purifier


What Is An Air Purifier?

Indoor air contains pollutants of all kinds, from dust particles, smoke, pollen, mold, etc. These pollutants can affect a person’s health and cause allergies since people spend the majority of their time indoors.

This is where an air purifier comes in, its job is to remove these pollutants and provide clean, fresh air for us to breathe. An air purifier can be a large whole-house unit or a smaller portable unit designed to clean the air in a room.

How Does An Air Purifier Work?

An air cleaner or purifier works by pulling in air and passing it through a filter(s). Filters can be of various types with some performing different functions. That is, filters generally either filter out gases like odors or particles like pollen.

Types Of Filters:

  • HEPA – A high-efficiency particulate air(HEPA) filter is the highest rated at removing particulate material at 99.97%.
  • Activated Carbon – Removes odors and gases from the air.
  • Electrostatic Ionizers – Work with an active electrostatic charge to charge and attract pollutants in the air.
  • UV Lamps – Ultraviolet lamps can kill airborne microbes that pass by the lamp.

Note that filters that remove particles from the air do not also remove odors and gases. Some air purifiers contain both types of filtration, so choose a portable air purifier to meet your needs.

To remove odors, consider a purifier with an active carbon filter + a HEPA filter, such as the Bissell Smart Purifier with HEPA and Carbon Filters for Large Rooms.

Or, step it up a notch and consider a medical-grade air purifier such as the IQAir HealthPro Plus – Medical-Grade Air Purifier with H13 HyperHEPA Filter for Particles, Gases, & Odors

What Should I Look For In An Air Purifier?

You want to look for the efficiency of an air purifier as well as its noise level. Part of the efficiency is the airflow rate, shown as clean air delivery rate(CADR). CADR is measured in cfm and shows how much fresh, clean air is provided. A higher CADR number is better.

Noise is also a factor in selecting an air purifier. If a unit is too loud, you may turn it off, thus removing its effectiveness at removing pollutants from the air.

When buying an air purifier have these considerations in mind:

  1. Size of the room to clean. Multiply the length by width of the room to get your square footage.
  2. What you want to filter out. Choose a filter for particles, odors, or both.
  3. The air purifier’s rating. Check its CADR rating and noise level.

According to the EPA, a 400-square-foot room should have an air purifier with a CADR rating of at least 260 cfm.

How Do I Select An Indoor Air Purifier?

Now that we know a little more about air purifiers, let’s put all that information together and talk about how to select one for your house.

As mentioned above, when looking into purifiers check their 1) CADR rating, 2) What it filters, 3) Its noise level, and 4) note the cost of replacement filters.

What It Filters:

To remove allergens and other airborne particles, select a unit with a HEPA filter.
To remove odors and other gaseous pollutants, select a unit with an active carbon filter.
To remove both particles and odors from the air, select a unit with both types of filters.

Its Noise Level:

An air purifier has internal fans that draw air into the unit and through its filters. This fan produces some amount of noise which can be disturbing to people nearby. If the noise causes you to turn off the air purifier, then it is not useful to own.

Look for the noise level on the specs of a filter, it should be listed as dBA(decibels). A lower dBA indicates a quieter air purifier and is what you want. Obviously, when you increase the fan speed to maximum, the noise will be louder than when the fan is at its lowest setting.

A good dBA level for a fan on a low setting is about 21 dBA, while on max. the level may be about 50 dBA.

As an example, I’ve listed the specifications of the Blueair Classic 605 Air Purifier from Amazon to show you what to look for. Note that Consumer Reports gave this a recommended rating of 88.

Blueair Classic 605 Purifier
CADR Pollen640 cfm
CADR Dust and Smoke500 cfm
Filter Type: electrostatic and mechanical filtration99.97%
Energy consumption15 – 100 W
Sound level33 – 62 dB(A)
Room Size775 ft.

Find The Right Purifier By Room Size

<200sq ft.

Medium 200-400sq ft.

400-600sq ft.

Extra Large >600sq ft.

Why Do You Need To Care About Indoor Air Quality?

Indoor air contains particles of various sizes that can affect your overall health. The concentrations of some pollutants can sometimes be 2 to 5 times higher in indoor environments than outdoors.

Very small particles( <10 micrometers) can be inhaled into your lungs and can lead to nose and throat irritation, and even heart issues. An air purifier mold killer can remove mold with a UV lamp to improve air quality.

Some common sources of air pollution particles derive from the outside, cooking, cleaning products, fireplaces, smoking, and more.

You can take steps to reduce your exposure to indoor pollutants by providing adequate ventilation around stoves, fireplaces, etc. Also, regularly change and replace the air filter in your home’s A/C unit. Finally, use an air purifier in rooms that you frequently are in for an extended amount of time.

Air purifiers can significantly reduce a room’s pollutants but are generally not effective to clean a whole house as most are designed for single room sizes.

How To Improve Indoor Air Quality

Although air purifiers are effective at improving the indoor air of your home, there are some additional steps you can take to help as well.

5 Tips To Improve Indoor Air:

  • Clean and vacuum your home regularly. Vacuuming and dusting are exceptional ways to remove pet dander and other particulate matter that have settled on and in surfaces.
  • Wash bedding and other linens regularly. Bed sheets especially get a build-up of skin cells, dander, and dust mites. Wash these and other linens and towels weekly to improve air quality and reduce allergens.
  • Open windows for fresh air. Opening your windows can provide fresh air into the home as long as the outside air is clean too.
  • Ventilate around cooking appliances. Use proper ventilation around cooktops and ovens to rid the kitchen of odors and other pollutants.
  • Replace the A/C unit’s air filter as scheduled. Your home’s A/C unit has its own filter that must be changed on a schedule. Some filters require changing every 90 days, whereas others every 6 months or so.


Not every purifier will fit your needs so shop around for an air purifier that fits the size of your space plus has the type of filter you need. This article has shown you what to know about air purifiers so you can make an informed purchase and find one that is right for you.

Quality Air Purifiers




Bissell Smart Purifier
w/ HEPA and Carbon Filters
for Large Rooms.

  • Active Carbon Filter
  • HEPA Filter
  • Large Room Coverage, filters 1252 sq. ft. with 1 air change/hour.
  • Quiet Fan Speeds

IQAir HealthPro Plus – Medical-Grade Air Purifier

  • Medical-Grade
  • Filters Particles, Gases, Odors
  • Filters particles 100x smaller than 0.3 microns, much smaller than a virus

Blueair Classic 605
Air Purifier

  • Extra-Large Rooms
  • Wi-Fi Enabled
  • HEPASilent technology

Frequently Asked Questions

How long does it take for an air purifier to be effective?

It depends on its size and CADR rating. It may be from 45 minutes to 1 hour to be effective in a room.

Should I sleep with an air purifier on?

Yes, it is most effective to run an air purifier continuously. If it is off it is not cleaning the air.

Do air purifiers dry out sinuses?

No, air purifiers remove pollutants from the air, they do not dehumidify or adjust the moisture in the air.

How do I know if my HEPA filter is dirty?

Two ways to know if the HEPA filter is dirty. First, visually check the filter. Second, look for an indicator light on the unit to tell you to replace the filter.

Can an air purifier help with coughing?

Possibly, it depends on the type of filter and allergens in the air. HEPA filters can reduce allergens in the air and be effective against coughing if used properly.