Electronic Air Cleaner: How to Select an Electrostatic Air Cleaner
How it works
An electronic air cleaner uses an electrical charge to remove particles from the air. The most common type is also known as an electrostatic precipitator and has a series of plates that the air is passed through. The first set of plates in the electronic air cleaner are negatively charged and that negative charge is passed onto the airborne particles that are moving through the electronic air cleaner. The second set of plates are positively charged so the airborne particles that received a negative charge are attracted to the positive plates.
Electronic Air Cleaner Advantages
- Permanent type filter so there are no filter replacements
- May use less energy
- May be quieter
Electronic (Electrostatic) Air Cleaner Disadvantages
- Poor performance for allergy and asthma sufferers and dust removal
- As plates become dirty the performance will further degrade
- On the filter rating scale it is considered a MERV 1 which is the lowest rating. A high efficiency HEPA filter will be around MERV 16
- Produces secondary pollution such as ozone and other gases
- Requires frequent cleaning. The California Air Resources Board who oversees ozone emissions from air purifiers has stated that most people do not properly maintain electronic or electrostatic air purifiers and as a result they can produce even higher levels of ozone. The interaction of ozone in a home has been shown to produce other gases such as formaldehyde.
Overall, the electrostatic precipitator is not a good solution if you are looking to remove allergens such as dust, pollen, mold, etc or if you are looking for very fine particle removal to address asthma or COPD. While the appeal to have a permanent filter is strong you do not get sufficient performance and introduce safety concerns through the production of secondary pollution such as ozone or formaldehyde.
Ozone and Secondary Pollution
Brands that use ionizers or electrostatic plates or brushes promote "zero ozone" or "ozone safe" to try to distance themselves from the generation of ozone. One issue with the testing standards for ozone is that it is not possible to accurately represent the actual environment where they are used and as a result an ionizing component can test safe or no ozone in a test chamber. The California Air Resources Board (CARB) certifies air purifiers in the US for ozone emissions. According to CARB's own research, "there is still a need to exercise caution because some devices could produce unhealthful levels of ozone in more realistic conditions, and secondary reaction products such as formaldehyde may contribute to the health burden as well. Caution also is warranted because introduction of any amount of ozone into indoor spaces may result in increased levels of formaldehyde, ultrafine particles, and other pollutants due to the reaction of ozone with terpenes (fragrance compounds such as pinene and limonene) and other chemicals emitted from modern consumer products and building materials. Additionally, operation and maintenance practices of air cleaner owners have the potential to significantly impact the amount of ozone produced. Recent survey results indicate that most California air cleaner owners operate their indoor air cleaning devices continuously and year round; however, owners typically do not maintain their devices as instructed by the manufacturer. This can lead to excess ozone generation and greater ozone emissions than observed in the tests reported."
Since the state of California passed a law in 2010 regarding ozone emissions there have been fewer electrostatic air purifiers sold as a result of concern for the emission of secondary pollution.
See how the electronic air cleaners compare to the listing of top rated air purifiers.