So, we have put together this guide to show you what to look for and to help you make a fair comparison.
As allergy and asthma sufferers ourselves, we believe what you should care about is having the cleanest air in your room or home so you don't breathe in harmful pollutants. Whether pollutants are “destroyed” or held in a filter, is irrelevant. The goal is to have the best indoor air quality.
Therefore, when we talk about performance, we mean how clean your air is in a living area.
But before we can answer the question of how our products compare in cleaning your air, we need to first consider what you are looking for the air purifier to remove.
AllergensMost people we talk with are looking for allergy relief from airborne particulates. This includes things like dust, pollen, mold spores, pet dander, etc.
For the removal of these airborne particles a true HEPA filter works best in providing the cleanest air. While this technology has been around for decades, we have not come across anything that can beat it for particle removal.
HEPA filters have the highest efficiency in removing airborne particles and this improves as the filter becomes dirty. For best performance the key is to have a highly efficient filter and good air flow. To learn more, see what is a HEPA filter.
In some marketing for electronic filtering technologies you are shown its ability to destroy allergens versus HEPA filters. There are two problems with this. One is that the air is moving quickly through the air purifier and to kill a virus you need much more contact time. If the air moves through in a fraction of a second why are you showing the disinfection rate based on hours of contact time? And two, to it does not show how clean the air in your room is.
Isn’t that the purpose of an air purifier?
How to Compare PerformanceThe industry standard for comparing air purifier performance in the removal of airborne particulates is called the CADR (Clean Air Delivery Rate). It utilizes a combination of the filter efficiency and air flow to show the volume of clean air produced.
The challenge for shoppers is only about half of the air purifier brands publish their CADR numbers so it is more difficult than it should be to compare.
The CADR number is something you should ask about before buying an air purifier. If the CADR is not shown in the specs, we have noticed it is often because the brand doesn’t want it known. Having good results is difficult because high efficiency filters, strong air flow and a low noise level are opposing forces.
Here are the certified CADR numbers for the EJ120 air purifier:
- Tobacco Smoke CADR: 323
- Dust CADR: 332
- Pollen CADR: 360
How to Compare when a Product Doesn’t Show the CADRSome brands will show something related such as the size of a room it will clean and maybe the associated air changes per hour.
While these are not independently tested and certified results, it’s something. Often, you will see this presented as 1 or 2 air changes per hour.
For example, you may see a 1,000 sq ft room coverage with one air change per hour.
Here’s how you can roughly equate this to a CADR.
The CADR is in CFM (cubic feet per minute). So, assuming the ceiling height is 8 ft, the 1,000 sq ft room has 8000 cubic feet (8 x 1,000). To convert to minutes divide by 60 to get to 133 cfm.
Assuming the filter removes 100% of the particles (which can be a big if), then the 133 cfm x 100% = 133 CADR.
Finally, compare this 133 CADR to the 323-360 CADR for the EJ120.
What Else to ConsiderWe believe the CADR is a starting point for comparison. It considers the efficiency and air flow through the filter however it does not show how efficient the filter is, how it will perform over time or the quality of the fan.
This is important since the most efficient filters will remove the smallest particulates and the more filter media it has the better it will do over time.
Filter QualityTo get to this, it’s good to know the quality and quantity of the HEPA filter media.
In the EJ120 the HEPA filter has been independently tested to remove 99.99% of particles at 0.3 microns. The testing was done with 3 units with these results.