air vs greenhouse gas

air

noun
  • understood as a gaseous mixture of nitrogen, oxygen, and various trace gases. 

  • The apparently open space above the ground which this substance fills, (historical) formerly thought to be limited by the firmament but (meteorology) now considered to be surrounded by the near vacuum of outer space. 

  • understood as a particular local substance with supposed effects on human health. 

  • A song, especially a solo; an aria. 

  • A jump in which one becomes airborne. 

  • A feeling or sense. 

  • The substance constituting Earth's atmosphere 

  • A sense of poise, graciousness, or quality. 

  • Nothing; absence of anything. 

  • Publicity. 

  • A breeze; a gentle wind. 

  • A television or radio signal; (by extension) media broadcasts in general. 

  • An air conditioner or the processed air it produces. 

  • understood as one of the four elements of the ancient Greeks and Romans. 

  • Pretension; snobbishness; pretence that one is better than others. 

verb
  • To be broadcast. 

  • To broadcast (a television show etc.). 

  • To discuss varying viewpoints on a given topic. 

  • To bring (something) into contact with the air, so as to freshen or dry it. 

  • To ignore (a person). 

  • To let fresh air into a room or a building, to ventilate. 

greenhouse gas

noun
  • Any gas, such as carbon dioxide, methane, or CFCs, that contributes to the greenhouse effect when released into the atmosphere. 

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