Do Air Purifiers Work for the Whole House?

Do Air Purifiers Work For the Whole House?

The two main air filtration methods are in-duct air purification and portable air purifiers; however, large-scale, whole house air purification systems are not a suitable option in many cases. An in-duct air purification system requires an HVAC system that uses forced air and typically costs more than $2,500, plus installation fees. If your home does not have an HVAC ductwork system to install filters in, you could consider purchasing individual air purifier units for your rooms.

Do air purifiers work for the whole house? While in-duct air purification systems are designed to work for the whole house, portable air purifiers are designed to filter for no larger than a specified area and have a cost range of $100-$1,500. A portable air purifier’s power is defined by its number of Cubic Feet per Minute (CFM), Clear Air Delivery Rate (CADR), and Air Changes per Hour (ACH). Best portable air purifiers for large rooms have high CFMs, CADRs, ACHs, and low noise level (dB). In addition to these metrics, features like High Efficiency Particulate Air (HEPA) filters, Photo Electrochemical Oxidation (PECO) filters, and activated carbon filters indicate higher quality and effectiveness.

Do Air Purifiers Work For the Whole House? Guide to Choosing an Air Purifier for Large Rooms

air purifier
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In what cases should you get a portable air purifier?

There are many reasons why someone might choose a portable air purifier over whole house purification systems. Portable air purifiers are better for those who have a smaller budget, rent the living space, live alone, or plan to sell their home later. Most portable units employ highly effective HEPA filters that whole house systems don’t have, and many of them come with convenient features like Wi-Fi control and Auto Mode. Because portable air purifiers do not require installation, they help you avoid secondary fees and expenses.

Types of Portable Air Purifiers

Mechanical models remove particles by forcing air through physical filters. They are good at capturing dust, pollen, pet dander and other allergens. Most manufacturers recommend changing the filter every 3-6 months, but the specific change rate depends on the model. Mechanical models can come with verified True HEPA filters that promise to trap 99.97% of all substances entering them. They can also come with activated carbon filters that serve as a pre-filter to remove odors and larger elements like pet hair.

Electrostatic or ion air purifiers capture particles on a collector plate by charging them with electricity. You can clean them by wiping off the collector plate instead of replacing the physical filters, which electrostatic air purifiers don’t have. Because these purifiers do not require fans, they are typically quieter than the mechanical models. However, they may produce trace amounts of the lung irritant ozone as a by-product of the ionization process. 

What to Do Before Buying an Air purifier

Before buying an air purifier, first measure the square footage of the space you will place the purifier in. You can measure the room’s dimensions with a tape measure, an app on your phone, a laser measuring tool, or you can reference your home’s floor plan if it is available.

Coverage Area

Portable air purifiers typically cover an area between 350 sq ft and 1,500 sq ft. For reference, the average living room in the United States is 340 sq ft, master bedroom is 200-350 sq ft, and standard size bedroom is 132 sq ft. You might come across some portable air purifiers that claim to work for the whole house, but it is more accurate to say they work for extra-large rooms than the whole house, since portable air purifiers can only filter the air in one room at a time. 

How to Choose an Air Purifier

When choosing an air purifier, look for models certified by the Association of Home Appliance Manufacturers (AHAM). Then check the model for these specifications:

  • Coverage Area – The recommended limit to how much area (in square feet) the air purifier should cover, assuming an 8 ft ceiling
  • Clear Air Delivery Rate (CADR) – Describes how well the air purifier reduces tobacco smoke, pollen and dust. Manufacturers recommend that the CADR be at least two-thirds the room’s area in square feet — so a 15×20 room (300 sq ft) would need a filter with a CADR rating of 200 cubic feet per minute (CFM). Having a manufacturer-provided CADR rating indicates that the purifier follows industry guidelines and has been tested in a certified test lab.
  • Air Changes per Hour (ACH) – The number of times an air purifier filters all the air in the specified coverage area within one hour
  • Decibel (dB) – The level of noise generated by fans in mechanical models

Next, look for these additional features that indicate higher quality and efficiency:

  • True HEPA filters – High Efficiency Particulate Air (HEPA) filters trap 99.97% of all substances entered. Dust particles can be as small as 5 microns in diameter, but True HEPA filters can capture particles down to 0.3 microns in diameter. An air purifier labeled simply as HEPA, HEPA-type, or HEPA-like are not as reliable as True HEPA, as only True HEPA filters promise the ability to trap 99.97% of particles 0.3 microns or larger.
  • activated carbon filters – Activated carbon granules have incredibly large surface areas and small pores that trap and remove odors, pollutants, and volatile organic compounds (VOCs). Activated carbon filters serve as pre-filters that capture larger contaminants before they fill up the HEPA filter, which is designed to trap more microscopic particles. The pre-filter can often be replaced separately from the HEPA filter, reducing cost by allowing the HEPA filter to be replaced less frequently.


Although portable air purifiers are designed to only filter one room at a time, they can do so more effectively than most in-duct air purification systems by using True HEPA filters and activated carbon filters. If you are looking for portable air purifiers for large rooms, be sure to check their coverage areas, CADR, ACH, and noise level, so you can purchase the most suitable air purifiers for your rooms.

Written by Ester Tsai

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