Purchase a moving water fountain for your home. According to the Kinetic Fountains website, whenever a water molecule is ruptured or splashed -- as they are in water fountains -- negative ions are emitted into the air. This also explains why we tend to feel healthier when walking along the coast or beside a waterfall: The movements of these natural bodies of water are releasing negative ions. By buying an indoor water feature, you'll be creating a source of negative ions in your own home.
Open windows, as stuffy, dry rooms are breeding places for positive ions. According to "Homes That Heal: And Those That Don't" by Athena Thompson, opening up windows is an effective way to increase the number of negative ions within your home, since they will be present in the fresh air.
Purchase an air ionizer for your home. Home-Air-Guide's website claims that air ionizers help to electrically generate negative ions, consequently enriching the air with these healthy molecules.
Cut down your use of electrical appliances. Avoid using air conditioning where possible: Peak Pure Air's website claims that these units strip the air of negative ions. Turn off the television and try to spend less time on the computer -- all of these appliances generate positive ions when in use.
Consider purchasing houseplants for your home. Wolverton Environmental's website claims that plant leaves produce negative ions when they are transpiring, or emitting water vapors into the air.