Yeah I lived maybe 100 meters from a busy road so I bought an air cleaner out of concern, but also got an Arduino with a serial device monitoring PM 2.5. PM 2.5 was always low teens or single digits, until I blew out a match next to the device and it went to 100s but dipped very quickly, so I think particulates aren't the biggest concern in most houses, unless maybe they spend all day with the windows open.