Health improvements are not measurable any more if you go below 5 mcg/m2 average level of PM2.5 particulates. For 50x reduction to be beneficial, you need to live in an area where the pollution is 250 mcg/m2, which is an extreme level found only in a few unfortunate places on Earth. 5-10x reduction is reasonable almost everywhere.
I know precisely the subjective difference between a 5x reduction and a 50x reduction. Only the latter feels sufficiently good to me, and my brain operates better with it. You will know it when you experience it. Maybe it's my middle-aged brain that needs the extra support. I live in an urban area near traffic. Lately there intermittently also has been wildfire smoke coming down from Canada.
