Your white noise machine is a fan blowing nowhere: Jeff Kaufman's case for a $47 purifier that makes the same hum and cuts bedroom smoke to 16% of outdoors
A small HEPA purifier sounds like a classic fan-in-a-box sleep machine. Jeff Kaufman ran the numbers: a 34-CFM unit at 45 dB takes a 10x10 room from AQI 200 smoke to about 72.