When Should I Use UV light on an Air Purifier? (or Not)

While UV light is often touted as a vital feature in many air purifiers, it may not be the best solution for purifying indoor air when misused. In this post, we'll give a precise answer on when you should use a UV light on an air purifier. We will also touch on how sterilization works and why it is a complementary technology to HEPA filters.


What is UV Light?

UV light is an invisible form of electromagnetic radiation that makes up about 10% of the sun’s output. It is commonly used in various technologies, such as arc welders, tanning beds, black lights, medical devices, water appliances, and of course, air purifiers. UV light is divided into three subcategories:

  • UV-A – Accounts for 95% of the sun’s radiation that reaches the earth and is used in tanning beds.
  • UV-B – Causes sunburns and is strongly linked to skin cancer.
  • UV-C – The most harmful to living organisms and cells, it is the type of UV light used in air purification due to its effectiveness and is generally safe for human use.

The Benefits of UV Light in Air Purification

UV light is an effective tool in air purification for killing living airborne organisms cells and disrupting their DNA. Air purifiers with UV light technology work by pulling air inside and passing it through a fine filter before exposing it to UV light in a small internal chamber. The prolonged exposure is crucial to the effectiveness of UV-C light, which is why it is often used as a complementary technology to HEPA filtration.

Should I Use UV light on an Air Purifier

When Should I Use UV light On Air Purifiers?

You should use an air purifier with UV light all the time without turning it off. Germicidal UV-C light is effective at destroying airborne contaminants such as mold spores, germs, bacteria, and viruses, permanently halting the allergens from growth. It complements the existing mechanical filtration by killing the microbes captured by the HEPA and carbon filter. As such, we highly recommend you get a HEPA air purifier with built-in UV light rather than a dedicated UVGI.

The Limitations of UV Light in Air Purifiers

  • Low dosage from coated bulbs is one of the main problems with UV light in air purifiers. In order to kill most pathogens and bacteria, a high enough dose of UV light is necessary. However, many UV bulbs are coated with a material that reduces the amount of UV-C emitted, making the intensity weaker and unable to kill viruses like COVID-19.
  • UV-C light needs prolonged exposure to be effective, the opposite of most air purifiers designed to move air quickly; therefore renders UV-C light less effective.
  • It is ineffective against some HEPA filters. A study on SARS, a close relative of COVID-19, found that UV-A light had no effect after 15 minutes of exposure. Similarly, UV-C light is limited in its germicidal capabilities due to its inability to penetrate dense surfaces like HEPA filters. Direct exposure to UV light is necessary to be effective, and HEPA filters make it impossible to ensure total visibility.
  • Some UV light purifiers are not capable of eliminating particulates, allergens, and particulate Matter (PM) commonly found in homes, including those that cause sneezing, coughing and transmitting diseases like COVID-19.
  • May contain highly toxic mercury in UV-C bulbs. If the bulb were to break, it would release mercury into your home, causing more harm than good.
  • UV light can be harmful if directly looked at; thus, it must be contained within the air purifier and not get released into the room.
  • There is a small risk of ozone byproducts emission, which can be harmful to those susceptible to ozone.

The "Other" Alternatives

While there is no denying that UV light is proven to be a safe air purification method, backed by many scientific studies and health agencies, including CDC and EPA, other technologies can also contribute to air purification. HEPA air filtration has been extensively peer-reviewed and established effective methods for purifying the air. It removes viruses, microbes, dust, and tiny particulate matter as small as 0.3 microns. Activated carbon filters use highly-porous charcoal to trap gas fumes such as odors and smoke, something UV light is not good at. Electrostatic precipitators release ions to remove industrial fumes, steam, and gas from the atmosphere. Never opt for an ozone generator as it is unsuitable for home use and not recommended by EPA, FDA, or government entities.

In Conclusion

UV air purifier is a wonderful device that should be used regularly to eliminate pathogens and provide clean, healthy air. Even though it has limitations and is no substitute for HEPA filtration, UV air purifier works best with mechanical filtration, as most health agencies would recommend. If you are getting one, we strongly advise getting a HEPA air purifier with UV-C light purification systems approved by AHAM.

Max Fernandez

A loving father and a dedicated reviewer for airfuji.com with more than 1000 air purifiers under his belt. Max Fernandez is also one of the million patients currently suffering from asthma. Feel free to nudge him if you have any questions.
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