In article ,
"MB" writes:
Four weeks ago I bought a room ionizer, made by Dezac Ltd, Cheltenham, that
is supposed to create all kinds of positive ions and at the same time grab

Negative ions, usually.

(filter out) particles circulating the room. Above the t & g ceiling
paneling is fibreglas insulation of which particles are circulating-- sun
rays show just how much, and I'm inhaling the stuff! Instructions that came
with the ionizer warn about all the dust that will be accumulating on the
table where it's standing, but after four weeks in use, there isn't any dust
at all. Can I assume it isn't functioning properly?

Does it have a row of needles pointing outwards?
Hold a mains neon screwdriver near these, and it should glow.
You might even feel a very slight breeze coming off them.

Don't open the unit up -- they normally have a something like
a 10 stage voltage multiplier to crank mains voltage up much
higher. The exposed needles will be current limited to a
harmless level, but the intermediate circuitry may well not
be.

--
Andrew Gabriel