July 22, 2021
When choosing an air purifier for your home or office, there exists a wide array of different features available from various manufacturers. What's important? What's silly? What's a marketing gimmick? Let's discuss some of the more common ones, why you might want them, and why you might not.
The first thing to think about should seem obvious, but the grade of HEPA filtration you are buying should be the first thing you think about. The two major variations of HEPA are the H10 through H12 grades, known commonly as "True HEPA", and the H13 through H14 grades, known as "medical grade."
By definition, all HEPA filters will remove at least 99.97% of particles 0.3 microns (micrometers) or larger. The most dangerous particles, however, are even smaller than that. The different grades of HEPA filters remove different levels of these smaller particles down to 0.1 microns. The highest grade HEPA, H14, removes 99.995% of particles down to 0.1 microns, while the lowest grade, H10, only removes 85%. This is, of course, a big difference!
Medical grade HEPA is commonly available and inexpensive these days, and it makes sense to opt for a machine that is at least H13. Remember: if you can't find any information about the grade of HEPA on a particular purifier, you can assume that it is a lower grade.
Some air purifiers use a second line of defense against air contamination: powerful UVC germicidal lights. Once the air has passed through the HEPA filter, it is bathed in UVC light before exiting the machine. Certain wavelengths of UVC light have been clinically shown to deactivate a wide array of viruses and pathogens that may be too small for the HEPA filter to capture.
Some manufacturers use mercury UVC lamps, which are extremely powerful and provide a strong germicidal effect. The downside is that the lamps need to be periodically replaced, are fragile, and may produce harmful ozone gas. The alternative is LED UVC lights, which are not quite as powerful as lamps but will last the lifetime of the device.
HEPA filtration removes a huge amount of airborne contamination, but it doesn't remove everything harmful. Activated carbon has special properties that allow it to remove volatile organic compounds (VOCs), odors, and gases from the air by trapping them on a bed of charcoal. Many air purifiers integrate activated carbon into their HEPA filters.
The biggest downside of activated carbon is its lifespan, which is much shorter than a HEPA filter and will be the first thing that needs replacement in your air filter. Since many activated carbon filters are integrated with the HEPA filters, this requires replacing the whole thing which can become expensive. However, if removing odors from you home is a top priority, it can be well worth it.
It's one thing to think your air is clean, it's another to know your air is clean. Many high quality air purifiers include sensors that monitor particulate matter in the air, volatile organic compounds, temperature, and more. It's common for air purifiers that are equipped with these sensors to offer an automatic mode, which automatically increases the fan speed is pollutants are detected in the air. By using automatic mode, the air purifier runs as energy efficiently as possible, which can be highly desirable.
It's a good idea to take note of what sensors are offered in the air purifiers you are comparing. Not all sensors are created equally, either. The highest end particulate sensors use laser light to measure particles down to the 1 micron level, giving the air purifier much higher sensitivity to invisible-to-the-naked-eye contaminants.
A custom app to control your air purifier remotely is becoming a common feature. This can be desirable if the air purifier has certain sensors, like humidity and temperature, that you may wish to see whenever you desire.
The downside is that Wifi typically comes with a considerable price on the air purifier for a feature that is likely to be more gimmick than useful. When set to automatic mode, a high quality air purifier should never need to be adjusted or monitored. It isn't uncommon for a manufacturer to include Wifi on a low quality air purifier simply as a marketing strategy, so beware.
Depending on where the air purifier is located, it may prove useful to select a model that has other features as well. Timers, for instance, are useful in school and office environments where 24/7 operation of an electrical device is undesirable. Child locks are popular in schools, where curious fingers can easily press buttons and alter the operation of the device. Some air purifiers offer a dimmer for any lights and controls, or even a "night mode", which is welcome for those who wish to use the air purifier in their bedroom.
There are a lot of things to consider when selecting an air purifier, and only you will know what is best for your home or office. The best advice is to know what's important, what isn't, and get the most affordable air purifier that meets your needs.