Air purifiers employ what seems to be simple technology on the surface. An effective air purifiers draws from the room with a fan, cleans the air, and sends it back out into the room. There are a number of ways cleaning is performed while in the actual system. We have provided a list of technologies which may or may not be used together in some air purifiers.
1. Adsorption- Adsorption uses a media like activated carbon or zeolite. These medias are porous so that the airflow is exposed to relatively large surface area. As the chemical contaminates come in contact with the media the chemicals combine the media and are thus removed from the room. Adsorption will remove chemicals and some parts of tobacco smoke and odors but has little impact on particles.
2. Mechanical Filtering- The second approach for an air purifier is mechanical filtering much like your furnace filter. In this case the room air is screened of particles however, the screen is very fine. An example of a very fine screen is a HEPA filter that removes particles as small as 0.3 microns. While an air purifier that uses HEPA will remove particles like pollen and mold spores they has little effect on chemicals so this technology is typically used in combination with some form of adsorption filter.
3. Electrostatic Filtration- These air purifier uses charged plates to give particles a charge of one polarity, positive for example, and a set of collecting grids or plates that have the opposite electronic charge, negative for example. As the charged particle nears the collecting grid it is drawn there by opposite charge on the collecting plate. As the particles build on the collecting plates the charging voltage will start to arc causing a popping sound. This is when you know it is time to clean the air purifier plates in the dishwasher. Another effective albeit unique technology is a hybrid between HEPA and electronic. Alen and Blueair Air Purifier models uniquely use electrostatic brushes to charge the particles prior to being mechanically filtered. This allows the Blueair air purifier to use HEPA with larger holes and thus get higher throughput.
4. Ultraviolet Light (UV)- While not strictly a cleaning technology, in the strictest sense, we will address it since it is a popular technology use in combination with others like HEPA or electrostatic filtration. UV is a light that neutralizes microorganisms such as bacteria and mold spores.
5. Pre-filter- Most all of the high-end air purifier models use some type of pre-filter in addition to the filter elements mentioned above. The purpose of a pre-filter in an air purifier is to extend the life of the fine filter such as a HEPA element by removing large particles before they can get to the HEPA filter. You will typically find visible dust, hair, and lint in the pre-filter. By keeping the pre- filter clean you can dramatically extend the life of your HEPA filter and improve the overall efficiency of your air purifier.
We have focused the above discussion on effective systems and specifically ignored air purifier technologies that use or produce detectable levels of Ozone or other non-fan based technologies. These are generally bad for you and your family.
The real key to addressing any Indoor Air Quality (IAQ) issue is the removal of the source of the pollutant or irritant if possible. We understand that if you love your cat to which you are allergic you have to deal with the dander but, if you are allergic to mold spores your first step is to determine the source of the mold and if possible, remove it. Secondly, if you have a whole house forced air system you need to make sure that your system is well maintained and that the filter is a high quality one that is changed regularly. Air purifiers can be used in any indoor space, and is recommended for allergy and allergy sufferers as well as those who suffer from chemical sensitivities. Those who are looking to simply improve indoor air from contaminants of a new home, garage or work spaces like nail salons and manufacturing plants can benefit from air purifiers.
As with many household appliances, maintenance is a key concern to the overall life of the air purifier, efficiency and effectiveness. To maintain your air purifier at top efficiency, the pre-filter should be cleaned on a regular basis. Regular cleaning will allow your air purifier to function with ease and this will translate into many benefits for you. Cleaning the air filter will help keep the noise level down because the airflow will not be constrained.