Influence　of　the　gassing　materials,　such　as　PA6,　PMMA,　and　POM　on　the　dielectric　properties　of　air　are　investigated.　In　this　work,　the　fundamental　electron　collision　cross　section　data　were　carefully　selected　and　validated.　Then　the　species　compositions　of　the　air-organic　vapor　mixtures　were　calculated　based　on　the　Gibbs　free　energy　minimization.　Finally,　the　Townsend　ionization　coefficient,　the　Townsend　electron　attachment　coefficient　and　the　critical　reduced　electric　field　strength　were　derived　from　the　calculated　electron　energy　distribution　function　by　solving　the　Boltzmann　transport　equation.　The　calculation　results　indicated　that　H2O　with　large　attachment　cross　sections　has　a　great　impact　on　the　critical　reduced　electric　field　strength　of　the　air-organic　vapor　mixtures.　On　the　other　hand,　the　vaporization　of　gassing　materials　can　help　to　increase　the　dielectric　properties　of　air　circuit　breakers　to　some　degree.