What are Negative Ions?

They're oxygen atoms with an extra electron.
And they can help you feel better.

"Remember that feeling you've experienced near a waterfall or high in the mountains? Those are two places that thousands of negative ions occur. They create an effect on human biochemistry."

"The normal Ion count in fresh country air is 2,000 to 4,000 negative Ions per cubic centimeter (about the size of a sugar cube). At Yosemite Falls, you'll experience over 100,000 negative Ions per cubic centimeter. On the other hand, the level is far below 100 per cubic centimeter on the Los Angeles freeways during rush hour."

"While ionization of the air is mandatory in many European and Russian hospitals and work places, it has only recently come to light in our country with the growing problem of toxic air in our urban environments."

Technically speaking: "Ions are charged particles in the air that are formed in nature when enough energy acts upon a molecule such as carbon dioxide, oxygen, water, or nitrogen to eject an electron from the molecule leaving a positively charged Ion. The displaced electron attaches itself to a nearby molecule, which then becomes a negatively charged Ion. It is the negative ion of oxygen that affects us the most."
From "Whole Self", Spring 1991, an article entitled "Ions and Consciousness."