Did a search of the forum.  Some old stuff, but not much.

Anybody used one of these (or equivalent) for flying or any other
circumstance?

http://www.weinproducts.com/minimate.htm

I ordered one today for for $90.  We're flying from Southern
California to Europe and I'm trying to get *all* my nasal ducks in a
row to keep the potential for illness down.

It *looks* like a zero-downside idea (apart from the ninety bucks!)

I found this study:

http://tinyurl.com/h5rvy

Evaluation of ionic air purifiers for reducing aerosol exposure in
confined indoor spaces.
Grinshpun SA, Mainelis G, Trunov M, Adhikari A, Reponen T, Willeke K.
Center for Health-Related Aerosol Studies, Department of Environmental
Health, University of Cincinnati, OH, USA. sergey.grinshpun@uc.edu

Numerous techniques have been developed over the years for reducing
aerosol exposure in indoor air environments. Among indoor air
purifiers of different types, ionic emitters have gained increasing
attention and are presently used for removing dust particles,
aeroallergens and airborne microorganisms from indoor air. In this
study, five ionic air purifiers (two wearable and three stationary)
that produce unipolar air ions were evaluated with respect to their
ability to reduce aerosol exposure in confined indoor spaces. The
concentration decay of respirable particles of different properties
was monitored in real time inside the breathing zone of a human
manikin, which was placed in a relatively small (2.6 m3) walk-in
chamber during the operation of an ionic air purifier in calm air and
under mixing air condition. The particle removal efficiency as a
function of particle size was determined using the data collected with
a size-selective optical particle counter. The removal efficiency of
the more powerful of the two wearable ionic purifiers reached about
50% after 15 min and almost 100% after 1.5 h of continuous operation
in the chamber under calm air conditions. In the absence of external
ventilation, air mixing, especially vigorous one (900 CFM), enhanced
the air cleaning effect. Similar results were obtained when the
manikin was placed inside a partial enclosure that simulated an
aircraft seating configuration. All three stationary ionic air
purifiers tested in this study were found capable of reducing the
aerosol concentration in a confined indoor space. The most powerful
stationary unit demonstrated an extremely high particle removal
efficiency that increased sharply to almost 90% within 5-6 min,
reaching about 100% within 10-12 min for all particle sizes (0.3-3
microm) tested in the chamber. For the units of the same emission
rate, the data suggest that the ion polarity per se (negative vs.
positive) does not affect the performance but the ion emission rate
does. The effects of particle size (within the tested range) and
properties (NaCl, PSL, Pseudomonas fluorescens bacteria) as well as
the effects of the manikin's body temperature and its breathing on the
ionic purifier performance were either small or insignificant. The
data suggest that the unipolar ionic air purifiers are particularly
efficient in reducing aerosol exposure in the breathing zone when used
inside confined spaces with a relatively high surface-to-volume ratio.
PRACTICAL IMPLICATIONS: Ionic air purifiers have become increasingly
popular for removing dust particles, aeroallergens and airborne
microorganisms from indoor air in various settings. While the indoor
air cleaning effect, resulting from unipolar and bipolar ion emission,
has been tested by several investigators, there are still
controversial claims (favorable and unfavorable) about the performance
of commercially available ionic air purifiers. Among the five tested
ionic air purifiers (two wearable and three stationary) producing
unipolar air ions, the units with a higher ion emission rate provided
higher particle removal efficiency. The ion polarity (negative vs.
positive), the particle size (0.3-3 microm) and properties (NaCl, PSL,
Pseudomonas fluorescens bacteria), as well as the body temperature and
breathing did not considerable affected the ionization-driven particle
removal. The data suggest that the unipolar ionic air purifiers are
particularly efficient in reducing aerosol exposure in the breathing
zone when they are used inside confined spaces with a relatively high
surface-to-volume ratio (such as automobile cabins, aircraft seating
areas, bathrooms, cellular offices, small residential rooms, and
animal confinements). Based on our experiments, we proposed that
purifiers with a very high ion emission rate be operated in an
intermittent mode if used indoors for extended time periods. As the
particles migrate to and deposit on indoor surfaces during the
operation of ionic air purifiers, some excessive surface contamination
may occur, which introduces the need of periodic cleaning these
surfaces.