For those that need to know every detail you can, here is a link to some "how it works" info on a Sharp Electronics web site, makers of the Plasmacluster filter technology.

http://www.sharp.ca/products/ion/index.asp

I've heard a lot of bad things about some ion filters, how they create too much ozone to be healthy and actually pollute the air. I haven't heard boo one way or the other on this technology. The web site kind of makes sense if you buy into it. I imagine Toyota would have taken the time to ensure the tech is good before licensing it from Sharp.

 

The Sharp Plasmacluster, from articles/info I've read, releases negligible amounts (if any) of ozone. You are safe inside the Camry. Diesel engine exhaust particulates alone will cause more lung damage than trace amounts of ozone possibly emitted from the air purifier.
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Ozone (O3) is an extremely strong oxidant. It's created by breaking apart H2O molecules. The extra O is then attached to an existing O2, thus the O3. Ozone, while good at protecting us from radiation, has a nasty habit of damaging brain cells, as well as other cells too.

However, the power output of the Ionizer in the TCH is so low that the amount of O3 created almost immeasurable. Humans can detect (smell) O3 in amount down to 0.01ppm. 0.1ppm causes us to have headaches. The amount created in the TCH is less than 0.0001. In other words, it would take 100x more just for us to smell it.

The advantage of the Ionizer is far greater than the disadvantage. The amount of "things' in the air that are filtered out would have causes much more damage then the O3 created.

http://en.wikipedia.org/wiki/Ozone

 

There is an easy fix for the oxidant problem - Blueberries. They have a strong anti-oxident content so spread a few on the dashboard to protect yourself.