Archive for the ‘General Commentary’ Category

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.


The Great Blue Light Panic Keeping Some Folks Awake

If you read alarmist comments on the inter-webs about the dreaded “Blue Light Hazard”, you may come away thinking that your TV, tablet, phone, and LED bedside lights are depriving you of sleep. Yes, the spectral power content, including blue light, can produce amplified melatonin suppression that can indeed disrupt your ability to fall asleep. And, yes, LED lights and many LED based displays do produce blue light at the wavelengths of greatest concern. We’ve been all over this, like here, and there have been thousands of other discussions on this everywhere, including in mainstream media – which for the most part get it all wrong. (more…)

EMF: Another Outrage Fizzle?

Posted: September 18, 2018 in General Commentary

There has been a bit of a to-do about EMF emission from LED products on the usual outlets carrying SM punditry.  The alarmist assert that EMF from lighting products is harmful to human health, and the EMF emissions from LED light sources is damaging to the eye.

Some of this may be founded on studies like ‘Electromagnetic Field Radiation and Your Eyes‘, published on the EMF-Health web site, which references ‘Scientists Link Eye Cancer to Mobile Phones‘ and ‘Cell Phone Radiation May Cause Visual Damage‘.  Another expert warning of EMF and electronic devices is Dr. Mercola, who wrote ‘The Real Dangers of Electronic Devices and EMF’s‘. (more…)

According to marketers of Twitter, Facebook, LinkedIn, Instagram, et al, social media is the engine of change, the foundation for bringing information and real transformation to the people. With Social Media, we will see the world connected and refreshed through the voices of the previously unheard. Social Media is the new light, the symbol of freedom and ultimate new world order founded on the concrete foundation of the first amendment, the true voice of “the People”. It has enabled revolution and advanced the human cause. It all sounds so… amazing and spectacular, if not completely incredible.

Behind the scenes, social media is actually just a software/app product that generates (more…)

Recently, there has been news hysteria about the availability of 3D printed gun plans, and the implications of such a product being made available to the general public. There are several facts that must be squared away before this “news” story can be effectively (more…)

Follow along, and see if this sounds familiar…

In the process of designing a new light, you begin by collecting manufacturer data sheets. You rifle through the LED data to find lumen output for LEDs and select one with a rated lumen output of 390@700mA, 3000K CCT / 90CRI (test current), and 188 lumens per LED at 350mA (calculated value), @ 3.4 Vf, for 158 lumens per watt. Nice!

You calculate what you need to make the target 1000 output lumens, and design a product around the data and calculations, use 7 LEDs operated at 350mA, to include 30% over the target to compensate for optical losses and temperature per the manufacturer data sheets. Using first article parts to build a prototype, you send it off to the photometric lab, expecting to see results very close to what you calculated. You can live with a minimum of 900 lumens, but hope to see better than 1000, as the data provided by the component providers indicates this should be the case. (more…)

The AMA has stepped in to take the stand that warm color LEDs are the only products suitable for street lighting. For anyone interested in this, please read it before assuming you know what it says. There are several factual errors in this document. Most in the lighting design business will see them. The LRC has issued a response to this document.  The IES has also issued its own response.   Again, for those interested, read all of these documents before blowing a gasket and spewing conspiracy theories into the realm, deriding the IES, the LRC or the AMA. It is probably worthwhile also to include the recommendations and statements of the IDA (Dark Skies) as they are the ones who actually initiated the <3000K solution. (more…)

Product development and management has evolved from the days of taking a shot on a hunch. In the days of fabricating products with minimal tooling, the risk of failure was low, and profit reward for success quite good. Who needed product management? Design it, build it, catalog it and get it to the reps and wait for the orders to roll in.

The lighting industry also has a long history of operating with lean management structures, particularly in small organizations. Ownership, Marketing, Engineering, Finance, Design, Engineering, and Sales all have a role in product development, planning and line maintenance. How well product management tasks are accomplished is (more…)

The “Internet of Things” has now become the newest, hottest marketing powerhouse. The scale of claims and the breadth of its application transcends lighting, so it eclipses popular lighting themes of Energy Efficiency and Human-Centric Lighting. The idea of everything being connected through the internet, accessible, upgradable, and monitored from anywhere at anytime is the big sell. Refrigerators that not only tell you when a product has expired, but automatically places an order for a replacement is one proposed far-reaching concept. Products that learn from our use cycles to adopt and send data to manufacturers for product development is another. Lighting that responds to local natural light conditions without local sensors. Power grids constantly adjusting in anticipation of user demand. Facilities managers, utilities, and end users accessing and monitoring building activity, condition, and (more…)

Full disclosure

I do not use, like, or support, the term “Human-Centric Lighting” or HCL, and the marketing of it. Nor am I convinced the bullish marketing of the term makes it any more attractive or legitimate. The term has been tagged onto so many crack-pot claims, unsupported promises, and misapplication of hand-selected, overly simplified misleading single-line extractions from legitimate studies, and anecdotal claims by unqualified “experts” – that it has become nothing more than an extension of the now discredited “Full Spectrum” marketing that has plagued lighting for decades. (more…)