Air purifiers typically have three layers of filtration media: a pre-filter for large debris such as dust and hair, an activated carbon filter for odors and VOCs, and a particle filter (usually HEPA) for very small particles. They’re meant to be run 24/7, usually with one air purifier covering a single room.
Some companies use UV lights to kill bacteria and viruses that enter into the air purifier’s filter. You can read about UV light’s effectiveness, or lack thereof here. In short, the amount of time needed to kill those viruses and bacteria is longer than the time they’re typically exposed to it in these air purifiers. Killing them is also not actually required — trapping them inside the particle filter essentially gives the same end result.
Ionizers release negatively charged ions into the air. Some airborne particles become attracted to these, latch onto them, and the combined result becomes heavy enough to sink to the ground. Unfortunately this process produces ozone as a byproduct, which can be harmful for humans to breathe in. Note that some vendors use marketing names like “PlasmaWave” (which is technically a bipolar ionizer) to avoid the stigma of ionizers and their health risks.
We also recommend only buying units with HEPA filters, not other proprietary particle filters.
Each unit listed below includes the area which the manufacturer claims it can cover. Sometimes these numbers are inaccurate. For example, there may be fine print that states a unit can only perform one air change per hour in such a room size, or the unit has to be in the middle of the room, or the ceiling can only be so high, etc. Please only use the advertised number as a general idea of how much space it can cover. For large spaces, it’s usually better to buy multiple smaller units than a single larger unit, assuming there are no other specific requirements. Doing so will provide multiple points of filtration.
Each unit has different cleaning and filter replacement schedules. Some have filters that last several years, while others require manual cleaning and buying of replacements every few months. While one unit may appear substantially more expensive than another, the cost of replacement filters and the time needed to clean them should be taken into consideration too. The higher initial cost sometimes makes up for the long-term cost.
The amount of activated carbon determines whether any given air purifier can practically filter out smells, smoke, and VOCs. Most low-end units include a very small amount that won’t actually make a difference. Carbon typically saturates faster than HEPA filters, so the ones with a small amount of it become entirely useless for gas filtration within a short period of time.
$450 Airmega 300 and $550 Airmega 400 for larger coverage areas and additional features
