This paper aims to characterize the polymer blends interfacing flowing air as a simulation of those used in large forced-gas cooled rotating machines and modern power transformers. Many factors have been investigated in order to show their effects on the current-voltage (I-V) characteristics. The results reveal that the air conditions play an important role in the I-V characteristics of polymer/flowing air/polymer gaps. The conduction current of such gaps increases with the air-flow rate and temperature, and decreases with pressure at high temperature. Also, it is found that there is no significant effect of the combined-crossed electric and magnetic (dc or ac) fields on the conduction current. Phenomenological explanations of the air-polymer-metal interfaces are introduced in the core of physicochemical reactions and injection processes. Also, derivation of the dependence of volume charge density inside the test section on flow velocity is introduced, which interprets the trend of the experimental results.