The filtering efficiency is a parameter that shows how much of a certain pollutant has the filter effectively removed.
Remember that the purpose of a filter of any kind is to take something, remove an unwanted part of it, and then give you the part of that original something that you really want.
When you make orange juice, maybe you only like the liquid and not the orange bits. You then go and take a filter so you can separate the juice from the orange bits, and as you know, all the orange bits stay with the filter.
An air purifier filter works the same way, but instead of orange juice we have air and instead of orange bits we have PM10 and PM2.5.
To calculate filter efficiency, the initial amount of PM2.5 concentration in a controlled small area is measured. Then the air purifier is turned on at max power and left to do its thing for around 15 minutes. After this time, the PM2.5 concentration is measured again so we can then calculate:
Filter Efficiency = 100*(initial PM2.5 – final PM2.5)/initial PM2.5
How we calculated the Filter Efficiency of the AirCleaner Personal
We didn’t! Because some specialist equipment is required, the Environmental Science Research Center and the Chiang Mai University did it for us.
To make this test, a fully sealed space with a stable PM2.5 concentration was set up by Dr. Wan Wariya. Then, a PM2.5 sensor with WiFi and data logging capabilities was placed inside to register the PM2.5 concentration levels.
The test results are publicly available and can be downloaded from the AirCleaner Personal website.
From the test results, it can be seen that the filtering efficiency of the AirCleaner Personal is up to 99.86%
Although it is not the ideal 99.97% filter efficiency that a HEPA filter is supposed to have, this is a real-world measured value that takes into account the whole air purifier and not just the filter.