This in Newtown, Kolkata. I was surprised that they had this public display. First, I have no idea if the public is aware of what those metrics mean. I, for one, had no idea what is PM10 and PM2.5 till I Googled them. Second, I have no idea whaat would anybody make of these metrics unless they sa what is good (or acceptable).

Full points for bringing awareness though. After all, I had to learn what is PM10 and PM2.5