TL-DR; 500 kV/m = 500 V/mm = 5V/um
This may be the breakdown of dirty air ( > 1 million particles /cu.ft. particles in air) or about 15% of clean dry air in a parallel plate breakdown voltage BDV. But it is the repetition rate of xx nanosecond discharge rates that control avg. energy levels. It could be sharp edge or point breakdown levels with less dust.
This is something I wrote a few years ago related to microscopic discharges for publication in "Transmission" a power line industry magazine where I knew the editor as a former UHV manager of R&D at ABB (where he conducted tests at >= +/- 0.5GV)
We have come a long way since
John Sealy
Townsend in 1890 with his discovery of
"
Avalanche Discharge", Negative Resistance,
Oscillation modes, EMI and formula for computing
Corona Inception Voltage in a charged gap.
Later F.W. Peek improved on this to create
Peek's Law. Now we just call it PD if inside or
Corona if outside because it is more rapid, easy
to hear/see, but it can also be inside. But all
Corona starts from PD and all PD starts from
a little contamination in a pure dielectric{insulation}.
================
Technical stuff
The E-field and its derivative are the prime forces that accelerate charged particles. When many capacitors are in series with HV, the voltage is largest across the smallest capacitance such that each pair of particles has the same Q=CV flowing through them. Moisture lowers the impedance 1/80 because its dielectric constant is 80 times dry air. It may be hard to predict when lightning strikes of an unknown microparallel plate will discharge, but it will certain never reach levels that you stated and are unlikely to exceed 3kV/mm or 3V/um by any significant amount unlike hard vacuum or something is added to raised the BDV threshold.
This will result in an avalanche effect ( negative resistance) just like a gas tube, lightning, and somewhat like other negative resistance semiconductors.The difference bein in air with H2 and O2 the air combusts usually with a visible spectrum and higher by breaking down the molecular chain into discrete molecules then with >4% Lower explosive level (LEL) for H2, it detonates. This ionization process can create UV which I believe the researcher you are reading (link pls) believes that with a high enough repetition rate , it can kill CV2 using Friis inverse square loss for distance from the e-Field. I believe this is a pipe dream. Just like RF can cause cataracts in eyes from conversion to InfraRed so too can arc welding and microarcs from this potential invention next to the skin.
Again if disinfecting food and other products, UV-C is a far better approach.
p.s. I wish I could cite all the research I did on this subject, but it is too lengthy and not useful for this thread.