These particle counters are aimed at home owners:
It has two readings, one for "small particles" > 1 um and another for "large particles" ("from approximately 5um and up"). It's obviously too coarse for professionals, but it might be useful for a home owner wondering what makes a difference. I just wonder about its reliability and durability; will it stop working after a year? Two? Five? Will it produce wildly variable counts, or reproducible ones? Has anyone used it? Does it have annoying quirks or notable weaknesses?