Air Purifiers with UV Light Benefits
It's time to quickly revisit high school and/or college science class. Remember the lessons about the rainbow and memorization techniques like ROY G BIV (Red, Orange, Yellow, Green, Blue, Indigo, and Violet)? Well, that covers what we call the "Visible Light" spectrum where various wavelengths of light are associated with what we describe and perceive as different colors. Outside the Visible Light spectrum is light with shorter wavelengths like Ultraviolet Light and X-Rays, and light with longer wavelengths like Infrared and Microwave.
|X-Ray||.01 - 10 nanometers|
|Ultraviolet Vacuum||10 - 200 nanometers|
|Ultraviolet C (UVC)||200 - 290 nanometers|
|Ultraviolet B (UVB)||290 - 320 nanometers|
|Ultraviolet A (UVA)||320 - 400 nanometers|
|Visible Light||400 - 700 nanometers|
|Infrared||700 nanometers - 1 millimeter|
|Microwave||> 1 millimeter|
Well, it just so happens that light with wavelengths in the range of 200-290 nanometers or UVC or UV C light is very effective at destroying small organisms like bacteria, mold, fungus, and even viruses. Interestingly, the maximum germicidal effect is at 254 nanometers which is typically chosen by air purifiers given the added advantage that at this wavelength ozone is not produced but rather destroyed.
Do UV Air Purifiers Work?
At the FDA website you can find the following about the effectiveness of Ultraviolet Light:
"UVC radiation has been shown to destroy the outer protein coating of viruses. The destruction ultimately leads to inactivation of the virus."
Why does this happen? UV irradiation works by breaking down certain chemical bonds and effectively alters the structure of the DNA and RNA which makes it impossible for a microorganism to multiply.
Given these scientific facts, some air purifier manufacturers take advantage of this knowledge by the use of UVC light by means of UVC lamps or UVC bulbs in their air purification systems. But, if you go off and do research you will find that the effectiveness of these air purifier technologies, namely, an Air Purifier with UV Light against various environmental concerns is largely dependent on three factors:
- exposure time to UVC Light
- distance from UVC Light
- power of UVC Light source
Hence, the FDA website states the following:
"In addition to understanding whether UVC radiation is effective at inactivating a particular virus, there are also limitations to how effective UVC radiation can be at inactivating viruses, generally.
- Direct exposure: UVC radiation can only inactivate a virus if the virus is directly exposed to the radiation. Therefore, the inactivation of viruses on surfaces may not be effective due to blocking of the UV radiation by soil, such as dust, or other contaminants such as bodily fluids.
- Dose and duration: Many of the UVC lamps sold for home use are of low dose, so it may take longer exposure to a given surface area to potentially provide effective inactivation of a bacteria or virus.
Not all UVC lamps are the same. Lamps may emit very specific UVC wavelengths (like 254 nm or 222 nm), or they may emit a broad range of UV wavelengths. Some lamps also emit visible and infrared radiation. The wavelengths emitted by the lamp may affect the lamp’s effectiveness at inactivating a virus and may impact the health and safety risks associated with the lamp. Some lamps emit multiple types of wavelengths. Testing of the lamp can determine whether, and how much, other wavelengths the lamp puts out."
To break it down for you, if you are moving air quickly through an air purifier there just isn't enough exposure time for the UVC Light to be effective given the power source that is practical in an air purifier.
For example, at 4 inches from a 6W UVC light source, it will take over 10 seconds to kill viruses yet air passes through an air purifier in less than a second. Thus, what you find is an Air Purifier with UV Light typically integrates UVC into the design as an additional component or feature of the product offering. Thus, HEPA filters are often employed to trap the harmful particles and then UVC Light ends their lives after several seconds of continuous, intense exposure.
However, there are filterless Air Purifiers with UVC Light that take a different approach. In particular, filterless UV air purifiers from Airocide leverage a technology originally designed at NASA. Air is pulled into the unit slowly and a UVC Light source strikes tubes coated with Titanium Dioxide (TiO2) which completely destroys airborne bacteria, mold, viruses, fungi, volatile organic compounds, and odors.
Hence, Airocide air purifiers are very effective at addressing very common indoor air quality concerns because the UVC light kills many harmful air pollutants. While you may not get a lot of air exchanges per hour in a larger space like other air purifiers with more powerful motors, you get a cumulative effect of clean air over time. You just turn the unit on and let it continuously run.
Are UV Air Purifiers Regulated?
While it is true you may find negative information about UV air purifiers, even lawsuits filed by lawyers wanting to profit off the negative press, the truth is the effectiveness largely depends on the product. But, rest assured, there are Air Purifiers with UVC Light that do indeed work very well and do kill bacteria and viruses, mold spores, etc., as established in laboratory testing. Although air purifiers are not regulated, UV Lights that are sold or distributed or used in products that make claims are regulated by the EPA under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). However, as an organization the EPA takes the following position about the safety and effectiveness of UV Lights:
"Unlike chemical pesticides, EPA does not routinely review the safety or efficacy of UV light devices and, therefore, EPA has not conducted a human health risk assessment to determine the safety of these products. For the same reason, EPA cannot confirm whether, or under what circumstances, UV light devices might be effective against any pest, including viruses and bacteria. The effectiveness of any UV light device will depend on a variety of factors including, but not limited to, the device’s duration of use, distance of the light from the surface intended to be treated, the UV wavelength, the specific pest being targeted, the strength or wattage of the UV light bulb, the age of the UV light bulb, shadow areas or other factors." - Compliance Advisory 2020
Which UVC Air Purifiers Are Recommended?
Filterless UV Light Air Purifiers
HEPA Filter UV Light Air Purifiers
Airpura's 2020 #1 Best Sellers
The HEPA Filter is in close proximity to a
Dual UV Lamp Source