UVC Disinfection

Posted: October 14, 2020 in General Commentary, Uncategorized

“Once more unto the breach, dear friends, once more..”

W. Shakespeare

For purposes of furthering the exchange of ideas and information on methods of applying SSL (Light) to address the Pandemic we find ourselves in….

I offer the following, posed as FAQs.

Can UVC light be used to deactivate the virus that causes COVID?

Short answer is Yes. It has been shown that UVC radiation between 200nm and 260nm, at energy levels of at least 25mJ can be effective in deactivation of viral contaminants as well as other bacteria/germs present.

Is UV safe for human exposure?

The short answer here, in two parts:

Yes, exposure to UVC wavelengths shorter than 230nm are considered safe for human exposure.

No, exposure to UVC wavelengths greater than 230nm are considered hazardous to human skin and eye tissue, and should not be considered for use where humans or animals will be present when the light source in in operation.

Can LEDs be used for UVC disinfection?

Another two part answer here:

Yes, when the space is empty, LEDs can be utilized that generate UVC light, at intensities and power levels that will produce a disinfection effect against COVID and other viral contamination.

No, if the intent is to expose the human occupants to the LED UVC radiation. LEDs are limited to wavelengths of greater than 254nm, which is considered harmful to humans.

So, what are samples of sources that are safe for human exposure?

The following are currently the leading, commercially available, verified products that produce safe far UVC radiation at power levels required to attain the target 25mJ to 250mJ energy levels to realize a real disinfection result, that is safe for human exposure:

Ushio Care 222. This is an emitter source that includes band pass filters to eliminate harmful UVC radiation above 230nm.

Healthe is a downlight cylinder product, one of a couple of form factors offered, that combine a 222nm light source with conventional LEDs to provide both Circadian support as well as disinfection.

Air disinfection is another way to approach UVC application to disinfection, where human exposure is not exposed to the light itself. Apache has a wide range of products for this purpose.

These products represent the type of product and quality necessary to avoid issues like happened in China, when children were exposed to unfiltered UVC radiation of the wrong wavelength for 9 hours.

Other products, like the Kenall Indigo Clean products are effective against some bacterial contamination, but are not effective against viruses. As noted in prior articles, viruses are not living organisms, so are not deactivated by light in the UVB or UVA regions.

Is Light Disinfection the Best Solution?

This requires a three part answer:

Yes, when the surface or air being disinfected can be directly illuminated, at energy levels required (power and time) to produce the desired result. While chemicals are effective, they are more difficult to apply evenly and consistently than can be achieved by illumination. Further, chemicals that are effective against viruses can also to be toxic to humans if improperly applied or disposed of. Light disinfection appears to be a solution for spaces, like food service, that are difficult to continually re-disinfect using chemical processes.

No, when the surfaces are not exposed directly to UVC light, as UVC does not reflect from most surfaces, and when it does, the reflected power level is significantly reduced – making indirect exposure unreliable. Further, when surfaces are dirty or contaminated (could even be from a cleaning agent), the UVC light may not penetrate, thus will have minimal to no impact. 222nm energy has a hard time penetrating many surface contaminants that appear to be invisible, so some care must be taken to insure the irradiated surfaces are clean of contamination.

Best Solution is to use UVC light disinfection in concert with other methods, such as safe chemical disinfection, which can be found as List N products at the CDC web site. The combination means that surfaces are properly cleaned to start with, increasing the efficacy of UVC disinfection, while those hidden from direct light are also covered. Using UVC light alone is not a strong strategy.

Finally, is this my last word on this topic?

Short answer is No.

Marketing vs. Reality

There is now a great deal of noise from marketers promoting the use of light as a disinfection tool. The current COVID19 Pandemic has fueled this effort and created a vehicle for many to roll out claims and campaigns that have varying degrees of relevance.

Read the rest of this entry »

Finishing the Big TR6 Project

Posted: September 18, 2020 in Uncategorized
Finished TR6 Project, ready for final tune, polish up and alignment (by others)

A long time friend (and previous employer) decided it would be lovely to take his car apart and rebuild it from the ground up. I have witnessed my of these “projects” over the years – most end badly. Taking a car apart seems so easy. Just undo every fastener, and dump the parts that fall off into boxes – while tossing all those old rusty corroded nuts, screws, washers, broken little clips and pins into bins. When something is frozen up, beat it apart, or cut it, it’s all replaceable – right?

Read the rest of this entry »

3D Printing is actually a misnomer. In technical terms, we are talking about AM (additive manufacturing.) The process delivers a 3 dimensional object in plastic or metal, layer by layer. Unlike CNC machining, which is technically subtractive in nature (starts as a block of material that is whittled into shape), AM produces no chips or cut-off material, just the finished part.

Read the rest of this entry »

The way we  access information is evolving. Where books and magazine publications were once the only reliable source of information, the evolution of digital media has blown some holes in the world of paper based media. By all indications, those holes are not going to heal, they are going to grow. The question is, will these holes tear the very fabric of print based information and advertising apart? Read the rest of this entry »

Recently commentary on certain news outlets, particularly friendly to the current occupant of the White House, have taken the stance that social restrictions are uncalled for and over-reactionary. To support their position, they state many examples of mortality statistics as proof that there are greater risks to health and well being than COVID19, that are not causing us to react at all.

These talking heads, and most of the statements they rely on, use of simplistic statements to defend a risky position. They are oblivious to the reality that in our slow reaction to Read the rest of this entry »

With the onset and spread of SARS-CoV-2 virus and the COVID19 it causes, I have seen many offer up the idea of using low cost UV light sources used primarily for curing resins and/or finger nail polish, as a method for sterilizing surfaces and used masks. Cutting to the chase… a $35 nail salon cure light is not going to work.

These sources use light between 365nm and 405nm, depending on the intended application. This is considered long wavelength UV light, or UVA (315 to 400nm). While these may be somewhat effective against some bacterial invasions, with extremely long exposures and/or very high intensity levels (well beyond those of a small cure light), there is no evidence this is a reliable sterilization solution for viruses.

To kill viruses, hospitals are now using UVlight robots that emit high levels of UVC radiation between 200nm and 280nm, and the primary germicidal range for UVC is between 254nm and 260nm, for periods of around 20 to 30 minutes – on top of chemical cleaning and sterilization procedures. The reason they use robots, is that this radiation is dangerous to human occupants, so is not done when anyone is in the room. UVC disrupts the DNA and RNA of micro-organisms, which prevents them from reproducing. Read Here for more on these machines and their use.

Read the rest of this entry »

A Common MacAdam Fail

Posted: May 24, 2019 in Uncategorized

The MacAdam ellipse is a Standard Deviation Color Matching (SDCM) protocol for describing visibility of human observers of differences of sources, by how far they deviate from a reference color. Each ellipse represents a standard deviation from the reference (center) source. It is generally accepted that within 3 MacAdam ellipses, most observers cannot discern a difference between two sources. At 4 steps, a significant sampling of observers would see a color difference. At 7, virtually everyone will see a difference. For a more complete background, there are numerous sources describing these details, such as https://en.wikipedia.org/wiki/MacAdam_ellipse. The shape of the ellipses varies by color, as human visual differentiation changes in both spectral sensitivity as well as range between sources.

With this, it would seem pretty straightforward that when someone claims their product, LED, or light sources fall within 2 or 3 steps, that it can be assumed that the difference between two sources from that provider will be unseen. Unfortunately, a common miss-interpretation and incorrect application of the MacAdam ellipse protocol creates an actual deviation that can be as much as double that stated. The illustration below shows how this happens. Read the rest of this entry »

The Adventure with Architectural SSL Magazine

In 2006, I pitched the idea of a magazine dedicated to Solid-State lighting technology as it applies directly to architecture with the owners of Construction Business Media. After a few pizza lunches and more convincing, they moved to creation of Architectural SSL magazine in time for Lightfair 2007 with its debut issue.

Since that debut 12 years ago, I have participated in editorial discussion and planning, contributed content to every issue with a market setting feature, a closing remarks Op Ed, white papers, judeged products, provided reviews of various products and provided general commentary on the progress of SSL into the lighting market. Read the rest of this entry »

Change of Plans and Direction

Posted: March 23, 2019 in Uncategorized


After significant evaluation of successes, personal goals, market direction, costs of operation, and future trends emerging – I have decided to make large scale changes to how we participate in the solid-state lighting market.

Pursuant to this, as of March 22, 2019, Lumenique, LLC has begun a complete overhaul/re-casting, starting with  the closing of our prototype and research facility in Menomonee Falls, WI effective immediately. This includes Tasca ending its 9-year pursuit of light cure products for curing fiberglass resins.

The principles of Lumenique, LLC/Tasca will be relocating to a new facility in Elgin Illinois, beginning mid- April. Until then, Lumenique is closed for business to focus on the monumental task of moving house and shop facilities. Both Angie and I can be reached by email and cell phone, should anyone wish to make contact, regardless of status of the business itself.

I will continue as Editor for Architectural SSL magazine and contributor to NZB magazine for Construction Business Media through the transition and beyond.

More details will be announced as things gel, and our new direction solidifies.


Kevin Willmorth