A negative ion generator is a device that emits a stream of negative ions into the air. The result is a cleaner fresher air due to the electrostatic settling of dust and the supposedly invigorating effect of breathing negative ions which are apparently found in abundance in the vicinity of waterfalls and mountain tops. In addition an ionizer can reduce airborne odors due to trace quantities of ozone produced at the tip of the ionization needles.
The principle of ion generation is simple. The electrical charge on an object is greatest at the sharpest point (that's why electrostatic generators favor big curvy domes for charge retention), so if a high negative voltage is applied to a sharp needle then the charge at the tip is so high that ions are literally thrown off and then repelled by the negative field on the needle. This results in a physical draught and a slight hissing noise. In a very dark room you will also see a faint purple corona glow on the needle tips.
Most technical wisdom suggests that while negative ions make you feel good, positive ions can cause headaches and nausea. This is why a negative ion generator can improve the perceived atmosphere in an office that has an unnaturally high positive ion balance.
According to manufacturers, reasons to purchase a Negative Ion Generator include:
High-density negative air ionization may be an effective alternative or adjunct treatment to light therapy and medications.