UV Air Purifier Myths, Hype, and our Observations

Nobody wants viruses, mold spores, or bacteria floating around in the air they are about to breathe. Just picturing those nasty pollutants swimming around in our lungs is enough to make the most rational among us seek an immediate solution. That’s exactly why some air purifier manufacturers include UV light in their machines. After all, hospitals use UV to kill a wide variety of viruses and bacteria, right?

What is UV Light and How Does it Kill Stuff?

Bottom line; UV light is electromagnetic radiation. It’s invisible to the human eye, produced by the sun, and comes in three distinct varieties. UV-A, UV-B, and UV-C.

The first, UV-A, is responsible for things like wrinkles and to a lesser extent, skin cancer.

UV-B, however, packs a bigger punch… and is the main contributor to tanned skin, sunburns, and skin cancer.

UV-C is the strongest of the three, and lucky for all of us most of it can’t get through the earth’s atmosphere. If it did we’d all be in a lot of trouble.

Why would we be in trouble, you ask? Because UV-C is a killer. It’s incredibly effective at killing various microorganisms without discretion. Through a process similar to the other UV rays giving humans a sunburn; extended exposure to UV-C breaks molecular bonds within the microorganism’s DNA.

From there, thymine dimers are produced… killing the organism. That’s why hospitals use UV-C to take care of viruses and bacteria that other sanitization methods might miss.

But, there’s a catch. First, to kill an organism with UV-C you’ll need a direct line of sight between the source and the intended target. If anything’s in the way, it simply will not work. Second, just like a suntan… or sunburn; UV-C requires a bit of time to effectively eliminate a virus or bacteria.

Enter, the value proposition. And, the UV Air Purifier.

Here’s where things get interesting. UV-C kills viruses, bacteria, and other nasty microorganisms… so theoretically, it should be great at taking out airborne microorganisms.

And, it’s in wide scale use… hospitals already use UV-C to sanitize a wide variety instruments, devices, and surfaces. If hospitals use UV-C it must be good. Every last air purifier should come with a government-mandated germ killing UV light installed. Right?

That’s exactly what some purifier manufacturers (perhaps unintentionally) lead us to believe. We need a UV-C lamp to catch anything that sneaks past the HEPA filter.

The claim, for the most part, is a misrepresentation. Or perhaps a misunderstanding of how UV-C goes about its passive killing spree.

So, to help you make an informed buying decision we decided to tackle a handful of the claims companies make about UV air purifiers. So, without further ado; here are some of the myths and claims air purifier companies perpetuate while selling their UV-C equipped killing machines.

Mythical Claim Number One: Ultraviolet rays kill the things a HEPA filter can’t capture.

This is the main selling approach used by UV air purifier marketers. HEPA filters are great at capturing anything .3 microns, or larger. And, since many viruses, germs, and other nasty pathogens are smaller than .3 microns… a HEPA filter is essentially useless.

Viruses and UV Air Purifier

So, the myth uses a half-truth to make you think that a UV-C lamp will kill anything that sneaks past other layers of filtration. The catch is that, as we pointed out earlier, UV-C takes its sweet time to kill unsuspecting microorganisms. And, since the airborne offenders are riding a fast moving stream of air, most of them will escape with little damage. Sure, some of the weaker ones might be zapped. Others might be trapped or slowed enough to receive a deadly dose of UV-C. But, for the most part, the same viruses that enter will sail through the machine without noticing your UV death ray.

Sure, some of the weaker ones might be zapped. Others might be trapped or slowed enough to receive a deadly dose of UV-C. But, for the most part, the same viruses that enter will sail through the machine without noticing your UV death ray.

Claim Number Two: UV equipped purifiers kill mold that gets trapped in the filter.

This is feasible. But, overall probably ineffective. The claim is that airborne fungi get trapped in your filter where it can set up shop and grow. Yuck. Then it sets forth releasing its offspring back into the air as it leaves the filter.

The problem is that UV-C requires a direct line of sight to kill. And, as you can probably imagine there are a lot of opportunities for fungi to seek out some shade in the filter media. So, the light might kill some of the fungi… but it probably can’t touch most of it. The solution; change your filter regularly and keep your home’s humidity in check. 

Claim Number Three: UV air purifier lamps are completely safe to humans.

For the most part, UV-C is safe. Despite our best effort, we cannot find any evidence of deaths or acute life-threatening injury caused by a UV air purifier. However, there are a few potentially harmful substances used in… or produced by UV-C generating lamps.

  • Mercury. In low doses, it’s a substance we should try to avoid. Unfortunately, many of the bulbs used in UV Air Purifiers use Mercury inside the glass casing. And, breaking one of these bulbs could expose you to Mercury vapor.
  • UV-C does not affect skin beyond producing minor irritation and redness. However, it can be harmful to your eyes. As far as we know there aren’t documented cases of serious injury to the eye, but you should avoid direct line-of-sight exposure.
  • Ozone. We’re one of the few review sites that consistently speak out against the harmful symptoms created when ozone is released into the air you breathe. Sadly, many UV-C lamps produce ozone. Oh, and one more interesting point; some Ozone generators actually use a type of UV lamp to produce Ozone. 

(Implied) Claim Number Four: The “technology” used in UV Air Purification justifies a premium price tag.

Without going into too much detail, or standing on our soap box… this is nonsense. Adding a cheap UV light bulb to anything shouldn’t increase its price by more than ten or twenty dollars. And, even that’s a bit of a stretch in our humble opinion.

If for some reason you ignore what we present here, do your own research, and still decide to buy a UV Air Purifier. Please don’t spend a bunch of your hard-earned cash “upgrading” to a UV-C equipped model.

Claim Number Five: (Insert Profession / Health Organization Here) recommends the use of UV-C to sterilize and kill harmful pathogens.

Everyone who sells a UV Air Purifier will lean on some study or recommendation from a professional health organization, government entity, or NGO. You’ll hear things like “in a study by” or “according to the World Health Organization…” but for the most part, those anecdotes and citations are misplaced assertions.

Yes, hospitals use UV-C to sterilize. The W.H.O. and other health organizations advocate the benefits of UV-C in certain environments. And, yes, it’s true that some high-tech, ultra expensive, facility serving HVAC systems successfully use UV light in their products. But, when it comes to a sub $150 room air purifier with a UV light bulb… those examples don’t really convey. More often than not, it’s because the duration of UV exposure in a hospital or high-tech system is much longer than your new purifier.

Here’s a great example of what it takes to kill the influenza virus (one of the weakest when it comes to surviving UV-C exposure). In this peer-reviewed article, researchers mention that killing the influenza virus requires “a few seconds” of high-intensity UV-C exposure. While low-intensity UV-C may take hours to have any significant impact. Once an infected person coughs or sneezes; the clock starts over. Which leads us to believe that it would be pretty difficult for a room purifier to effectively neutralize even the weakling influenza virus. And, another interesting thing to consider; according to this study UV-C’s efficacy decreases as relative humidity increases. Maybe that’s why we haven’t seen any UV air purifier and humidifier combo units.

Our Recommendation

Do your research before buying into the hype of UV air purifiers. We’re sure you’ll see that they aren’t as effective as many manufacturers claim. Does that mean you should avoid a purifier with a UV lamp? Not necessarily. There are actually some great purifiers out there that come with a UV light. And, in many cases, those purifiers are offered at a very reasonable price.


UV Air Purifier

This unit from GermGuardian is one of our absolute favorite purifiers. We love it. However, it comes with a UV lamp.

So what do we recommend? Just ignore the UV lamp, manufacturer claims, and turn the light off if you can. There’s no reason to waste electricity if you don’t need to. If the purifier has the other specs you’re searching for (like a HEPA filter) buy it. Just don’t assume that a light bulb is magically zapping airborne pathogens as they fly through the air purifier on a stream of fast moving air.

Before any angry manufacturers cut loose with harsh comments and critiques of the opinions we just shared, let us provide the following disclaimer. We aren’t providing conclusive evidence or medical advice. Nor are we trying to say (or imply) that manufacturers are maliciously trying to pull a “fast one” on consumers.

We are simply attempting to share our observations and theories on why a consumer should think twice before believing everything the read in Internet reviews/product descriptions. And, before we go there are some purifier manufacturers who do make some convincing arguments contrary to our current stance on the issue. The one purifier company that stands out is RXAir. Take a look at what they have to say and decide for yourself.

Here are some other interesting things to consider

The FTC (Federal Trade Commission) ordered a handful of manufacturers to stop promoting UV air purifiers as an effective defense against various viruses.

The EPA (U.S. Environmental Protection Agency), on their website, warns consumers about air purifiers outfitted with UV lamps. Claiming bacteria and viruses pass through before UV-C is able to make an impact.

Related: GT-3000 Fight Stubborn Odors with Ozone

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