dirtying vs pollution

dirtying and pollution both are nouns.

Word	Noun	Adjective	Verb	Adverb
dirtying	Yes	No	No	No
pollution	Yes	No	No	No

As nouns, pollution is a hyponym of dirtying; that is, pollution is a word with a more specific, narrower meaning than dirtying:

dirtying: the act of soiling something
pollution: the act of contaminating or polluting; including (either intentionally or accidentally) unwanted substances or factors

Other hyponyms of dirtying include maculation, spotting, staining, contamination.

dirtying (noun)	pollution (noun)
the act of soiling something	the act of contaminating or polluting; including (either intentionally or accidentally) unwanted substances or factors
	undesirable state of the natural environment being contaminated with harmful substances as a consequence of human activities
	the state of being polluted