I don't see how. Any time you have a plasma you have Coulomb collisions between the electrons and ions. This leads to bremsstrahlung, which contains UV. The cooler and less dense the plasma, the less the radiation, but it is always there.
To expand on what Doc Watts says, most glasses are only transparent at optical frequencies, and are opaque in the UV (i.e. they block out UV light). Quite handy for view ports on plasma deposition systems (unless they're actually made out of quartz and you're getting yourself a sun tan in the lab).
Melles-Griot has transmission spectra (and other information) for a wide range of materials in the Material Properties Chapter of their excellent Laser Optics primer / text on their website:
Direct link to the http://www.cvimellesgriot.com/Products/Documents/TechnicalGuide/Material-Properties.pdf" [Broken]