Attraction/repulsion between currents has nothing to do with any air between them, unless I missed something in your setup.
It is a problem of electrostatics very well established and a typical example for studying special relativity. It has been discussed here many times. See thisthis.
When the two currents flow in the same direction and you change frame, you end up with static charges. Taking into account length contraction, you find the correct repulsion between the wires.
