polluted vs rarefied

polluted

verb
  • simple past tense of pollute 

adj
  • made unclean or impure 

  • drunk 

rarefied

adj
  • Distant from the lives and everyday concerns of ordinary people; esoteric, exclusive, select. 

  • Elevated in style or nature, sublime; of high intellectual or moral value. 

  • Less dense than usual; thin. 

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