The products on our list range from a whisper-quiet 20dB to a rather noisy 52dB but it’s worth noting that many in the lower range refer to when an air purifier is in its lowest and least powerful, mode. It really depends on the model, but a big selling point of air purifiers is ones that work quietly. If using an air purifier in the bedroom, look for designs that offer sleep modes, which limit sound and light that could come from the machine.