Why would someone want negative Ions in their home?

Question:I just bought a dehumidifier. It has this option on it that you can push to have it put negative ions into the air. The instruction manual tells you only that negative ions 'create an atmosphere similar to a waterfall.'

But, didn't I just buy the damn thing to make my apartment a lot less 'like a waterfall?'

Why would anyone want negative ions in their air??!

Answers:
Negative ions help clean the air. They bind to positive particles floating in the air (most pollution is +) and fall to the ground or table. You may have to dust of vacuum a few more times a month but it's better than breathing it.

The waterfall thing is a bonus. Lightening caused neg ions in nature. If you have ever gone outside right after a thunderstorm and smelled how fresh the air is--well, that's due to the neg ions.