It probably started when I was much younger with much worse asthma and always had a HEPA filter running in the background. Eventually this turned into basically always having some kind of fan in my primary locations. Right now I dig the Coway air filters on low or medium.
Even beyond the alleged "noise floor dopamine boost", I find some kind of background whoosh really nice for masking otherwise variable sounds, such as cars, airplanes, and the wind, which are far more distracting.
10/10 would recommend running some sort of air filter all the time. Plus, cleaner air (air pollution has all kinds of bad effects).