Water vapor is then a pollutant.
You could look at it that way I suppose, but there would be no life on this planet without it. Greenhouse gases in the right proportion have a vital beneficial effect on our climate, without a proper level of them in Earth's atmosphere it would be an uninhabitable ball of rock alternating between freezing at night and sizzling hot during daytime.
We're having a severe drought here in the southeast, and I would love to have some of that "pollutant" condense and fall as rain around here before my 550 ft well goes dry again.