The first thing you need to do is place the air purifier in your bedroom and turn the unit up to the highest speed for at least 30 minutes or 2 hours. You should decide this according to your room size. So if you have a small room, 30 minutes is enough. If you have a large room then 2 hours minimum is enough.
Once you do this step, then you should not turn off the air purifier immediately. You should let it run for at least 3 more hours. This step is crucial since if you turn it off, then the pre-cleaned levels will return right away, and you need to repeat the first step. This is all you need to do to keep the normal and safe air in your room.