Also known as Electrostatic Precipitators, these have been used by emissions of particulates. They operate by electrically charging a field between conductive plates. Incoming particles are given a charge opposite of the charge on the collector plates where they accumulate.
Pros: They are effective in removing smoke from the air that passes through the filter. They do not reduce airflow as most other filters do. They can be installed in central units or in each room.
Cons: They require frequent cleaning. They only remove particulates from the air that are within the reach of the ions. The particulate build-up can act as a breeding ground for bacteria.
When high voltage is applied to a conductive surface that is not grounded, electrons will build up until they find a place to "jump off." A sharply pointed surface, such as a needlepoint, allows the negative ions to easily escape and ionize the air surrounding the point. Negative ions travel through the air until they attract airborne particulates that agglomerate until they are too heavy and settle to the floor
Pros: They are effective at removing smoke from the air. They do not reduce airflow.
Cons: Needlepoint ionization emits ions in a very focused stream, causing the particulate in the immediate air to become negatively charged, while walls and surfaces remain positively charged. These negatively charged particles will then become attracted to the nearby wall and stick to it, causing a phenomenon known as "black wall" (unless a metallic conductive plate is used).
Units that use only negative ions as an air cleaning method are limited in their effectiveness. Negative ions, while beneficial, are not as powerful as other ions, such as hydroxyl ions and hydro peroxide ions, that can destroy viruses, bacteria and germs and chemicals, nor are they as effective at eliminate odors, unless there is an element of ozone created as a by-product of the ionization creation.
We carry two brands that produce negative ions. Surround used Needlepoint Ionization and Air Oasis uses the more advanced photocatalytic oxidation technology:
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