How Do Electrostatic Air Cleaners Work?

The filtration process described

• An ionizing purifier is an alternate name for an electrostatic air cleaner and better describes its filtration process. This type of air filter uses a method called "corona discharge," which creates charged molecules called ions.

  Atoms that are present in the air contain a neutral charge; that is to say, they are neither positively nor negatively charged. The corona discharge creates a small electromagnetic field, and any atoms that pass through one side of the field gain an extra electron and become negatively charged. Atoms that pass through the other side of the field lose an electron and become positively charged.

  Particles in the air such as dust are considered large targets, and they are highly likely to be ionized when they pass through the field of the corona discharge.

  Air that passes through the corona will no longer contain neutrally charged particles and will hold a either a positive or a negative charge. Electrostatic purifiers contain a series of metal plates, half of which are charged positively, and the other half negatively. When the charged air particles pass by, they are attracted to the oppositely charged plates, and they begin to accumulate on them. The dirt and debris that gathers on these plates are the charged particles being filtered out of the air.

  Particles that don't pass through the metal plates still are accounted for. The oppositely charged particles in the air will attract each other, forming larger clumps of particles. Eventually they become too heavy to remain in the air and settle to the floor as dust.

Strengths and weaknesses

• The biggest strength of electrostatic air filters is that they can neutralize viruses, bacteria, pollen and cigarette smoke. They are generally quiet and have a low electrical operating cost.

  A weakness of this type of air filtration is that it does not remove odors, nor will it remove any dangerous chemical particles such as radon gas or carbon monoxide. The filter will accumulate large amounts of dirt as well, and must be cleaned and washed from time to time.