You are supposed to change your BlueAir HEPA filter every 6 months. There is a display that tells you when to change it. I decided to see how long I could use my HEPA filter before changing it. I judged the effectiveness using my AirVisual Node. Today my air purifier finally struggled jeep my bedroom below 50 AQI. Hence I changed the filter today.
Below is my HEPA filter change in Shanghai last year after six months of usage.
This photo was after six months of usage in Saigon.
I definitely will change it after six months now. I just wanted to see if it would work. I was trying to go for a full year but could not.