Ionizer, UV and Photocatalysis
Ionic air purifiers work in a completely different way than filter air purifiers. They release a continuous flow of negatively charged ions into the air. Those ions connect with airborne particulates, making them negatively charged as well.
Over time, all of those negatively charged particles group together, become heavy, and fall to the ground or onto nearby surfaces. In fact, those negatively charged ions will be attracted to anything positively charged, like television screens and tabletops.
A summary offound that most ionizers score “near the bottom of the effectiveness ratings” ( ). They concluded that most ionizers are too weak to have an effect.
There’s no question that ultraviolet light can neutralize and destroy many types of bacteria and other contaminants – as long as it’s given an ample amount of time to do so.
The problem with UV air purifiers, though, is that they run the air through far too quickly and the UV light doesn’t get enough time to really perform its task. The air gets circulated in, is briefly zapped, and is circulated back out again – usually with the same levels of contaminants as it had in the first place. So it’s not in contact with the UV light long enough for it to effectively kill any bacteria.
The catalyst that cleans the air is typically titanium dioxide (sometimes called titania) and it’s energized by ultraviolet (UV) light. UV is the short-wavelength light just beyond the blue/violet part of the electromagnetic spectrum that our eyes can detect. There’s no question that photocatalytic can neutralize and destroy many types of bacteria and other contaminants – as long as it’s given an ample amount of time to do so.
The problem is primarily because air flows in and out of an air purifier, so it’s not in contact with the photocatalysis long enough for it to effectively kill any bacteria