pollutant vs repellent

pollutant

noun
  • A foreign substance that makes something dirty, or impure, especially waste from human activities. 

repellent

noun
  • A substance or treatment for a fabric etc to make it impervious to something. 

  • Someone who repels. 

  • A substance used to repel insects, other pests, or dangerous animals. 

adj
  • Repulsive, inspiring aversion. 

  • Resistant or impervious to something. 

  • Tending or able to repel; driving back. 

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