impair vs pollute

impair

verb
  • To weaken; to affect negatively; to have a diminishing effect on. 

pollute

verb
  • To make something harmful, especially by the addition of some unwanted product. 

  • To violate sexually; to debauch; to dishonour. 

  • To make something or somewhere less suitable for some activity, especially by the introduction of some unnatural factor. 

  • To corrupt or profane 

adj
  • Polluted; defiled. 

How often have the words impair and pollute occurred in a corpus of books? (source: Google Ngram Viewer )