| An air filter is a sieve that catches airborne | | | | actually have filters, or have problems, costs, and |
| particles, human and pet hair, volatile chemicals, | | | | limitations not mentioned in advertising. |
| and odors, removing them from the air. But many | | | | Ionizers |
| filterless air purifiers filter less! A central vacuum | | | | While many filtered air purifiers are marketed as |
| cleaner system just blows the dirt outside, but air | | | | "ionic", true ionizers simply emit ions into the air. |
| purifiers without filters must do something with | | | | These cause airborne particles to clump together, |
| the impurities removed from the air. | | | | growing until they become heavy enough to fall |
| The air purification market is filled with shameless | | | | to the floor or stick to walls, draperies, and |
| hucksters pushing "free" goods or using arcane | | | | furniture. |
| terminology to obscure the dangers or costs of | | | | While simple ionizer air purifiers are filterless, the |
| their products. It's well known that one major air | | | | dirt is not gone. It will become airborne again |
| cleaner marketing scam is selling the filtered air | | | | when weather changes or drafts stir. Ionizers |
| purifier cheap as a loss leader for high priced | | | | gather only particles, so unless they have high |
| replacement filters. But just as frequent is the | | | | ozone emissions there is no chemical/odor |
| "costless" siren song about never having to buy | | | | removal. |
| replacement filters. | | | | Ionizers using both polarities, positive and negative, |
| The notion of an effortless air purifier sure | | | | to charge airborne impurities, can create an |
| appeals to me. That's why I like automatic | | | | oxidation environment which surrounds water |
| operation and air filter replacement intervals up to | | | | molecules in the air, destroying particles and |
| 5 years. While that is close to the lowest possible | | | | inactivating microorganisms. Called |
| user exertion, and is very low maintenance, it is | | | | "plasmaclusters", this is typically incorporated as an |
| not filterless. | | | | add on to HEPA filtered machines. |
| Electrostatic | | | | Photocatalytic Oxidation: "PCO" |
| The majority of air cleaners sold as not requiring | | | | The air purifying technology which has the best |
| replacement air filter media are electronic: | | | | chance of producing a truely filterless air purifier is |
| electrostatic precipitators. This includes market | | | | photocatalytic oxidation (PCO). |
| leaders Ionic Breeze, Oreck, and Friedrich C90, as | | | | No filters are required for PCO systems, which |
| well as a host of filterless air purifier wannabees. | | | | may be as simple as a single painted florescent |
| These air cleaners electrically charge airborne | | | | light bulb. Ultraviolet rays excite metal |
| impurities and then gather them on an oppositely | | | | semiconductors, which produce oxidants capable |
| charged collectors or grids. Where does the | | | | of destroying smaller particulates, chemicals, and |
| accumulated mess go? Inside the air purifier! Most | | | | odors. |
| of it builds up on the metal collection plates or | | | | Since the tiniest particles are the deadliest and |
| grids. | | | | most difficult to filter conventionally, PCO is a |
| These collectors must be cleaned very frequently, | | | | technological breakthrough. |
| or they begin to let dirty air slip past. As time | | | | Pollutants, both chemicals and particles, are not |
| passes, especially where there is cigarette | | | | captured, they are vaporized, gone, changed into |
| smoking or grease frying, the collector plates build | | | | carbon dioxide and water. While PCO can actually |
| up an oxidized film layer. | | | | be filterless, filters are usually used to capture |
| This film layer can be very difficult to remove. | | | | larger particles, to big to burn up. |
| When this insulation builds up, electrostatic forces | | | | Photocat systems still require annual replacement |
| of attraction diminish, leading to bypassing, | | | | of the ultraviolet lamp, so are not zero |
| sparking, and lowered capture rates. Particles may | | | | maintenance. |
| also stick to the inner parts and surfaces of the | | | | A couple examples of PCO purifiers are the |
| machine, pouring out when it is turned on. So | | | | Nanobreeze and Pionair |
| many so-called filterless air purifiers end up being | | | | HEPA filtered air purifier technology is the |
| the filter. | | | | standard by which emerging filterless air purifier |
| Once the colector plate is oxidized, wires and | | | | concepts are evaluated. No perfect filter free air |
| connectors damaged, or surfaces poorly mated | | | | cleaner has been developed, most have risks or |
| causing arching and ozone, you get to buy a new | | | | defects. I encourage everyone to try the PCO |
| collector plate. These are costly. | | | | and Plasmacluster technologies, and not to be |
| So the electrostatic models are not really filterless. | | | | fooled by pie in the sky marketing. |
| Electrostatic "filterless" air cleaning devices may | | | | |