polluting gas emission
/pəlˈuːtɪŋ ˈɡas ɪmˈɪʃən/
n
English · polluting gas emission中文 · 污染气体排放Español · emisión de gases contaminantesFrançais · émission de gaz polluants
意味：Most polluting gases are present in the atmosphere in minuscule quantities, but human activity increases their concentration.