Air Flow, Performance and Air Changes Per Hour – Considerations for Purchase of Air Purifiers


The air that we breathe in is just as crucial as the foods and beverages that we consume. When it comes to health of humans, the quality of air surely plays an important role and in the presently highly polluted world, making the air in your house purified should be one of the top priorities. Now, if you have decided to invest on an air purifier, among the many considerations to make, there are three important considerations that will help you in arriving at the ideal purifier and here is the list of these three factors:

  • Air Flow
  • Performance
  • Air Changes per hour

Let us gather some details in this regard:

Air flow:

There is a term called ‘Air Flow Rate’ in air purifiers. This rate denotes the level of air that passes through the purifier over a specific period of time. As air is actually a gas, its measurement can be done either by its mass or by its volume. However, manufacturers use volume as the measurement.

The air flow of air purifiers is denoted as Cubic Feet per Minute or CFM. Generally, air flow relies on two factors and they are the power of the fan that is present inside the air purifier and second is the efficiency of the filter that is present inside the unit.


When talking about performance, the question that should arise in your mind is how to determine the performance of the air purifier and the answer to this question is that you can determine the performance on the basis of air flow and air changes per hour.

Air Changes Per Hour:

This is actually denoted as ACH in the air purifier niche and this rate shows the number of times the entire volume of air within your room is replaced within a period of one hour. So, when you find that the manufacturer has specified this rate in higher number, it can be better. This means that higher the number of changes, better will be the quality of the unit. You will find that the number of air changes per hour varies from 1 to 7 and 7 is stated to be the most efficient rate.


Irrespective of the size of your room and irrespective of your requirements, it is suggested that you can consider air purifiers that can perform 2 or more air changes per hour. This can be the ideal number, particularly, if your home has everlasting source of contaminants and allergens.

In short, you will have to do a slight mathematics to keep yourself informed about the factors that need to be considered during the purchase of best rated air purifiers to ensure the purchase of the ideal unit. The thing you will have to remember is that before investing on any unit, it is better to read as many reviews as possible about the unit to feel satisfied before investing.