I recently constructed a plasma-type ozone generator to eliminate
cigarette smoke odors from a piano used by a heavy smoker.  I tented
the piano and ozone generator with a plastic tarpaulin and ran the
ozone generator for 12 hours.  I then circulated outdoor air through
the room containing the piano for 24 hours after turning off the
generator, to remove the residual odors produced by the ozone reactions.
The result is an instrument free of smoke odors.

It is worth noting that the ozone concentration required to remove
odors is significantly above personal safety levels.  I strongly
recommend that anyone considering the use of ozone generators for
deodorizing purposes consult an authority other than the manufacturer
of home air cleaners.  Here is a link to one credible source:

  http://www.epa.gov/iaq/pubs/ozonegen.html

This EPA web site cites numerous studies and clearly lays out the
risks (substantial) and benefits (questionable) of using ozone for
bacteria and odor reduction in the home.  You can extrapolate from
the discussions what precautions are necessary for safe operation
when deodorizing a musical instrument.

John D. Rhodes - RPT
Vancouver, Washington