DA wrote:
tim wrote:


Are you sure they are 'ozone' air purifiers? Ozone is a no-no in
interior spaces and has been for years. Back in the mid 80s when
DEC brought out their original LN03 Laswer Printer I remember
getting a little package in the mail which was an 'ozone filter'
because the electrostatics in the printer mechanism were putting
out more ozone than was allowed.

If they are ozone, then yes, it happens quite readily. An example
I will always cherish came from about the same time frame at one of
the Big 3 parts supplier plants. They had one of those self-
contained office buildings inside the plant at the receiving docks
to house a couple of minicomputers that ran the receiving software.
Unfortately, they had had some custom programming done to link the
two computers that was not compatible with later versions of the
operating system needed to run newer models. The problem came in
in that the battery chargers for the fork lifts were about 20ft
away from this building, and the ozone they put out was enough to
make all of the insulation on the computer backplanes brittle. So
any time field service had to replace a board, they almost always
wound up replacing the wiring harness as well. Needless to say,
there was a lot of pressure to do something about the ozone.

Hi Tim,

Thank you for the insight. Well, sometimes they are advertised just like
that: "ozone air purifier". Sometimes they do not stress the word ozone,
but in any case, no matter what the label says, those no-moving-parts
purifiers are all designed around one principal. The air passes by
high-voltage charged metal plates, gets charged (and some of the oxygen
splits and combines again as ozone) and then flows towards another pair of
opposite charged plates that the dust and other particles flock to due to
the electrostatic charge. I cannot think of any other way to build an air
filter with no moving parts.

I thought of one other implication: they also sell a car purifier. As a
matter of fact it often goes as a "free" gift with the big one. It's
pretty maddening to think about what this thing can do the car's electric
wiring if it's on all the time.


Cheers!
D.

Consumers Reports web site has a new article on-line this month (10/05)
updating a previous report they did on air purifiers a couple of years
ago. Now, I know some folks in this ng aren't big CR fans but when it
comes to quantitative testing of functional things like this, I figure
they know what they're doing.

No marketed air purifier should claim to produce ozone, as it is
hazardous in all the ways mentioned above; of those that work on the
ionizing principle that you describe, some do produce measurable ozone,
and some produce more than others. One famous catalog merchant's unit
came under particular criticism for very heavy ozone and general
ineffectiveness; the CR report details the enusing lawsuit, which was
apparently settled in CR's favour. The updated article is about equally
unimpressed with that merchant's updated machine. If you're considering
dropping a couple of hundred bucks on one of these, it's well worth it
to get the paid access to the CR site.

My gut feeling is that any that are dumb enough to *claim* to produce
ozone probably do nothing at all. CR had hard time finding ones to
recommend, even among the priciest; apart from producing ozone, most of
the units just didn't work worth a darn.

Chip C