air-performanceIn this article, I will describe the main parameters you must know before purchasing an air purifier for home. For example, an air purifier that is very effective at collecting dust is an excellent choice for people who live in cities where there are plenty of airborne dust particles. Then again, people who are suffering from asthma and allergies want to pay much bigger attention to pollen, and dust mite which is the greatest issue for them.

No doubt, they need to look for air purifiers who removes dust mites and pollen more effectively. These, of course, are air purifiers which have combined HEPA and activated carbon filters.

Also, the third group – pet owners can obtain a lot from air purifier systems. What connects all above mentioned people categories together? Mainly, it`s the air purifiers real life performance, which can be quite different from the numbers in specifications. The reason for this articles is to shed some light on this field before you spend your hard-earned money on quite pricey air purifier equipment.

How to determine the performance of an air purifier

There a ton of informational articles about the performance on the web, but sadly most of them are about HVAC unit efficiency. As you seek for a portable air purifier, these articles wouldn`t be helpful to you. I wrote this informational guide to explain you main performance features of portable air purifiers; you must know.

Three main features determine air purifiers performance, which is the number of air changes per hour, air flow rate and CADR rating (Clean air delivery rate). Clean Air Delivery Rate deserves its page, and I will only explain the first two on this page.

Air Flow Rate

The air flow rate represents how much air goes through the air cleaner over a defined period. The same as others gasses the air can be measured in two ways, by its mass or volume. Air purifier manufacturers are interested in volume, the same as I and you.
Air purifier air flow is shortened to CFM (cubic feet per minute). An air purifiers air flow is determined by two main factors, filters efficiency, and power of the fan inside purifier.

(ACH) Air changes per hour

air-change-per-hourThe ACH (air change per hour) shows you many times per one hour the whole air in the room changes. ACH usually varies from 1 to 7, an air purifier with ACH 7 will be the most efficient.
Notwithstanding on your needs and size of the rooms, I recommend going for air purifiers that can perform at least two air changes per hour. Or at least, ACH of 4 if your home has a permanent pollution source, which brings contaminants and allergens into your house.

While going through reviews and searching for an air purifier bear in mind how big ACH would be you like to have. Notice that some cheaper units are not so efficient, they have their ACH only when running at a maximum speed which can be quite noisy. More sophisticated premium air purifiers will provide higher ACH number with lower overall settings and also will be much less noisy.


Mainly, manufacturers have included ACH and CFM numbers in the reviews. But sometimes they have not, so you need to do some light math. Which is worth it and will help you to choose the best air purifier. If air cleaner manufacturers didn`t include these numbers in product specification, I tried to do that on my site.