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Fact Sheet on UV Disinfection for COVID-19 (2021 update)

Fact Sheet on UV Disinfection for COVID-19

The scientific community now strongly believes that UV disinfection technologies can play a role in a multiple barrier approach to reducing transmission of the virus that causes COVID-19, SARS-CoV-2, based on current disinfection data and empirical evidence. UV is a well-known disinfectant for air, water and surfaces that, when used correctly, can help reduce the risk of infection from contact with the COVID-19 virus. Leading experts from around the world have gathered to develop a guide to the effective use of UV technology as a disinfection measure to reduce transmission of the COVID-19 virus.

It should be noted that "UVC", "UV disinfection" and "UV" as used here and in the scientific, medical and technical literature refer specifically and importantly to UVC light energy (200-280nm light) in the germicidal range, which is not the same as UVA and UVB radiation used in tanning beds or sun exposure.

Facts about UV and COVID-19

Can UVC help prevent the transmission of COVID-19 by reducing contamination?

Based on the available evidence, scientists believe so. Here's why:

  • UVC light has been used extensively for more than 40 years to disinfect drinking water, wastewater, air, pharmaceutical products and surfaces against a whole range of human pathogens. All bacteria and viruses tested to date (many hundreds over the years, including other coronaviruses) respond to UV disinfection. Some organisms are more sensitive to UVC disinfection than others, but all tested to date respond at the appropriate doses. For info about the Fluence (UV Dose) Required for up to 99% disinfection from Viruses, Bacteria, Protozoa and Algae , based on 413 reasearch papers, read our related article.
  • UVC disinfection is often used in conjunction with other technologies in a multi-barrier approach to ensure that any pathogen that is not 'killed' by one method (e.g. filtering or cleaning) is inactivated by another (UVC). In this way, UVC could now be installed in clinical or other settings to supplement existing processes or shore up existing protocols when they are exhausted by excessive demands due to the pandemic.
  • COVID-19 infections can be caused by contact with contaminated surfaces and subsequent touching of facial areas (less common than human-to-human, but still a problem)[vi]. Minimising this risk is critical as the COVID-19 virus can survive on plastic and steel surfaces for up to 3 days[vii]. Normal cleaning and disinfection may leave some residual contamination that can be treated with UVC, so a multiple disinfectant approach is advisable. UVC has been shown to achieve a high level of inactivation of a close relative of the COVID-19 virus (i.e. SARS-CoV-1, tested with an appropriate dose of 254nm UV while suspended in liquid)[viii]. Scientists believe that similar results can be expected in the treatment of the COVID-19 virus, SARS-CoV-2. However, the key is to apply UVC in such a way that it can effectively reach all remaining viruses on these surfaces.
  • There is widespread agreement with CDC guidance for hospitals that the germicidal efficacy of UVC is influenced by the UVC-absorbing properties of the suspension, surface or aerosol in which the organism is located, by the type or spectrum of action of the microorganism, and by a variety of design and operational factors that affect the UV dose delivered to the microorganism (


The scientific community recognizes that in cases where the UVC light cannot reach a particular pathogen, that pathogen is not disinfected. However, in general, by reducing the total number of pathogens, the risk of transmission is reduced. The total pathogen load can be significantly reduced by applying UV light to the many surfaces that are easily accessible, as a secondary barrier to cleaning, especially under hurried conditions. This would be a relatively simple matter of illuminating relevant surfaces with UVC light, e.g. the air and surfaces around rooms and personal protective equipment.

UV light, specifically between 200-280nm[i] (UVC or the germicidal range), inactivates (aka, "kills") at least two other coronaviruses that are close relatives of the COVID-19 virus: 1) SARS-CoV-1[ii] and 2) MERS-CoV[iii] [iv] [v]. An important caveat is that this inactivation has been demonstrated under controlled conditions in the laboratory. The effectiveness of UV light in practice depends on factors such as exposure time and the ability of UV light to reach viruses in water, air and in the folds and crevices of materials and surfaces.

Are UVC disinfection devices safe?

Like any disinfection system, UVC devices must be used properly to be safe). They all produce varying amounts of UVC light with a wavelength of 200nm-280nm. This UVC light is much "stronger" than normal sunlight and can cause a severe sunburn-like reaction on your skin. The target tissue in the eye would be the cornea (and not the retina). The effect on the cornea is called photokeratitis, which is also known as sweat flash or snow blindness, so it's like sunburn of the eye. It is unlikely that any of the UVC light will pass through the cornea and then the lens to reach the retina as it is a short wavelength (i.e. high frequency).

Some devices also produce ozone as part of their cycle, others produce light and heat like an arc welder, still others move during their cycle. Therefore, general machine and human safety must be considered with all disinfection equipment and these considerations should be addressed in the operating manual, user training and relevant safety regulations.

Are there performance standards and UVC validation protocols for UV disinfectors?

Given the wide range of UVC devices marketed for disinfection of air, water and solid surfaces, the lack of uniform performance standards and the widely varying degree of research, development and validation testing performed on different devices, the scientific community strongly recommends that consumers exercise caution when selecting devices and look for evidence of third-party testing and certification of device materials and electrical components by well-known organizations such as NSF, UL, CSA, DVGW-OVGW or other international requirements.

For UVC devices intended to inactivate air and solid surfaces in the healthcare industry,the scientific community is working intensively with national standards organizations in the lighting and healthcare industries to develop disinfection test standards[x]. The goal is to develop guidelines that will help healthcare providers worldwide select the best possible technologies for their facilities in the fight against multidrug-resistant organisms and other pathogens[xi], such as the COVID-19 virus.




[i] “Miscellaneous Inactivating Agents - Guideline for Disinfection and Sterilization in Healthcare Facilities (2008);” Centers for Disease Control and Prevention, National Center for Emerging and Zoonotic Infectious Diseases (NCEZID), Division of Healthcare Quality Promotion (DHQP) (

[ii] “Large-scale preparation of UV-inactivated SARS coronavirus virions for vaccine antigen,” Tsunetsugu-Yokota Y et al. Methods Mol Biol. 2008;454:119-26. doi: 10.1007/978-1-59745-181-9_11.

[iii] “Efficacy of an Automated Multiple Emitter Whole-Room Ultraviolet-C Disinfection System Against Coronaviruses MHV and MERS-CoV,” Bedell K et al. ICHE 2016 May;37(5):598-9. doi:10.1017/ice.2015.348. Epub 2016 Jan 28.

[iv] “Focus on Surface Disinfection When Fighting COVID-19”; William A. Rutala, PhD, MPH, CIC, David J. Weber, MD, MPH; Infection Control Today, March 20, 2020 (

[v] Ibid.

[vi] “Preventing the Spread of Coronavirus Disease 2019 in Homes and Residential Communities”; National Center for Immunization and Respiratory Diseases (NCIRD), Div. of Viral Diseases (

[vii] “New coronavirus stable for hours on surfaces”; CDC (extracted from N van Doremalen, et al. Aerosol and surface stability of HCoV-19 (SARS-CoV-2) compared to SARS-CoV-1. The New England Journal of Medicine. DOI: 10.1056/NEJMc2004973 (2020) (

[viii] “Inactivation of SARS coronavirus by means of povidone-iodine, physical conditions and chemical reagents;” Kariwa H et al. Dermatology 2006;212 (Suppl 1): 119 (

[ix] “Ultraviolet Radiation and the Work Environment (Revised. See: 74-121),” The National Institute for Occupational Safety and Health (NIOSH), Page last reviewed: March 29, 2017 (

[x] “Pathway to Developing a UV-C Standard – A Guide to International Standards Development”, C. Cameron Miller and Ajit Jillavenkatesa, IUVA News / Vol. 20 No. 4, 2018

[[xi] “Healthcare Associated Infections Workshop Advances Development Of Ultraviolet Disinfection Technologies,” IUVA Press Release, dated 24 Jan 2020 4:14 PM (

Highly efficient disinfection UVC LED systems


UV Fluence (Dose) recommended for 90% or 99% disinfection from Viruses, Bacteria, Protozoa and Algae

UV Fluence (Dose) recommended for 90% or 99% disinfection from Viruses, Bacteria, Protozoa and Algae

 When designing, building or installing a UV light, two key questions must be answered first:

"How irradiance does it need to have?"

"What is the required exposure time?"

While there are many studies that show the effectiveness of UV light in disinfection or sterilization, a high variance of the results exists, which presents a challenge to find an answer to these questions. 

We will present our recommendations by analyzing the results of 413 reasearch papers, as found in the compilation "Fluence (UV Dose) Required for up to 99% disinfection from Viruses, Bacteria, Protozoa and Algae"  that can be downloaded at the links below:

PDF: Fluence (UV Dose) Required to Achieve Incremental Log Inactivation of Bacteria, Protozoa, Viruses and Algae

The research studies present the fluence required to achieve a log reduction from 1 to 5, for different types of UV sources.

The effectiveness of sterilization or disinfection with UV light depends on the exposuretimewavelength and irradiance.

  • Exposure or fluence (sometimes called dose) is measured in mJ/cm2 (where 1 mJ/cm2 = 10 J/m2)
  • Exposure time is measured in seconds (s), minutes (m) or hours (h)
  • Irradiance is the flux of radiant energy per unit area, in other words how much of the UV radiation power (measured in W = 1000 “miliwatts” mW = 1.000.000,00 “microwatts” μW ) reaches the surface. Irradiance is measured in mW/cmor W/m2 (1 mW/cm2 = 10 W/m2) and is dependent on the radiant power, distance and dispersion of the radiation emitted by the lamp source.

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Advice for the purchase and use of equipment for the UV disinfection of air and surfaces

This article is intended as a guide for those who are considering purchasing UVC disinfection equipment. These tips should only be considered as suggestions.

Attention buyers! - There are few recognized standards for equipment designed for UVC disinfection of air and/or surfaces. As a result, there are many advertisements and promotions claiming amazing performance with little or no scientific support.

  • Ask the seller for copies of scientific papers that prove that his device actually works as he claims. The scientific work(s) should show the actual reduction of a test micro-organism in the environment in which the device is intended to work. 
  • Does the product have suitable built-in UV safety sensors for automatic shutdown or does safe operation depend entirely on the operator?
  • Does the device comply with NIOSH, UL, IEEE and related safety standards in the country of sale?
  • Does the unit emit/generate ozone? If so, does it meet NIOSH requirements. How is the ozone attenuated? (We recommend avoiding ozone equipment, as it poses a safety risk to operators, unless ozone is specifically part of the treatment process and is used in a controlled and safe manner)?
  • Is the device used to disinfect medical devices? If so, is it compliant with the requirements of the regulatory body in the EU, USA or country of sale?
  • If the device is a UV rod that is used to disinfect a surface (e.g. a worktop or an envelope)

The technical specifications should state the UVC irradiance at a fixed distance from the UV front of the device (e.g. 10 mW/cm2 at 2 cm).

The UV dose (irradiance multiplied by exposure time in seconds) should be at least 20-40 mJ/cm2 to inactivate viruses on perfectly flat and ideal surfaces (details in this article). Thus, if the irradiance at the target surface is 10 mW/cm2, the exposure time should be 2-4 seconds. However, the presence of microscopic gaps on flat surfaces can inhibit disinfection, and disinfection on other materials, such as cloths, may require completely different doses. For example, disinfection of viruses on medical masks may require doses as high as 1000 mJ/cm2. This is a subject that is currently being researched and our current understanding changes almost daily.

With any UV device, you must NOT look at the UV light or expose your hands from the UV side. UV light is a source of skin burns/cancer and can quickly damage the eyes.

Remember that UV disinfection is based on a "line of sight" between the UV lamp and the target surface. If the UV rays are shaded by texture elements on the surface, the shaded areas may receive much less UV light or no light at all. Disinfection effectiveness is therefore determined by the UV dose to which these areas are exposed.

Like any disinfection system, UVC equipment must be used properly to be safe.

They all generate different amounts of UVC light in wavelengths from 200 - 280 nm. UVC light is much more energetic than normal sunlight and can cause a severe, sunburn-like reaction on your skin and could also damage the retina of your eye when exposed.
Some devices also produce ozone as part of their cycle, others produce light and heat like an arc welder, and still others move during their cycles. In general, all disinfection devices must therefore take into account the safety of both man and machine.

These considerations should be taken into account in the operating manual, in user training and in compliance with appropriate safety regulations.

Mid Power LEDs it test: Nichia 757G is the leader

As a manufacturer, we aim to use the top performing LEDs in our LED strips and modules. We are particularly focused on mid power LEDs, those that usually use less than 0.3 Watt of energy, are fairly small and require minimal or no cooling. A big share of our products use these LEDs.

Before choosing the best performing LED for our products we have compared more than a dozen models from the top LED manufacturers: Nichia, Osram Opto Semiconductors, Samsung, Philips Lumileds, LG Innotek, Seoul Semiconductor, Cree, Everlight.

For a meaningful comparison we selected LEDs that function at 65 mA with a voltage between 2.75 and 3.2 V, classified in three groups:

  • Cold White (5000-6500K), CRI 80+, for linear fluorescent replacements (LED tubes) or lighting fixtures for the office or industry
  • Warm White (2700K-3900K), CRI 80+, usually used in LED lamps, linear lighting fixtures, cove lights, desk lamps, usually for residential and hospitality sectors
  • Warm White (2700K-3900K), CRI 90+, with applications in luxury lighting, professional linear lighting fixtures, cove lights for commercial and hospitality sectors

For each category we compare the luminous flux and luminous efficacy at the usual junction "lab temperature" of 25ºC and at a more realistic 100ºC. The comparison data is that from the manufacturers datasheet.

We also added the performance data of average 5050 and 3528 LED packages because such LEDs are still used by many lighting manufacturers today, with applications including linear led modules, fluorescent tubes, lamps, panels or even luxury lighting fixtures.

Cold White (5000-6500K), CRI 80+, for LED strips and modules for the office or industry.

Nichia 757G LEDs have the highest performance and efficacy at 25ºC and 100ºC, with 37.5 lumen and 210 lumen / watt and 33.75 lm and 189 lumen / watt respectively. They also have the lowest performance difference between "lab" and "reality" operating temperatures, at only 10%.

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Disinfection with UV Light can deliver 99% Kill Rate for Bacteria and Viruses (incl COVID-19)

UV light breaks the DNA of viruses and bacteria

Effective and cost efficient disinfection or sterilizing of surfaces, water and objects can have a significant, positive effect on the general health of our society. The impact of pandemics, present such of the COVID-19 (coronavirus), and future can be greatly reduced, as well as a major decrease of illnesses in general, including from drug resistant pathogens or hospital-acquired infections (HAI).

Disinfection or sterilization with ultraviolet (UV) light can be the way to achieve such goals. However, challenges of using UV light still exist and the ways to overcome them are presented in this article.

"UV light annihilates viruses and bacteria by destroying their ability to reproduce. "

Using ultraviolet (UV) light to disinfect or sterilize1 has actually been embraced by some hospitals since years, by using large, industrial-grade machines to kill microorganisms (including COVID-19) in hospital rooms or on furniture, objects, clothing or instruments. However, such machines are the perfect showcase of the challenges of using UV light. They are prohibitively expensive for private or business use, as a mobile platform with UV lamps can cost more than 60.000 USD2. Their deep UV radiation is also dangerous for people and must be used only in empty rooms.

UV robot for hospital use

With the current advances in UV LED lighting technology both problems can be overcome.

Smaller versions of UV disinfection lamps can be built at affordable cost, so they are accessible to consumers and companies looking to clean pretty much everything, from office spaces, elevators and living rooms, to phones, computers and even toilet seats.

Different UV wavelengths with precise control of intensity and radiation pattern can make disinfection safe to be used when people are present.

The most promising practical application of the above is the continuous disinfection with low intensity UVA LEDs .

"Continuous disinfection: UVA radiation functioning for 8 hours, daily. Safe for people*. Will kill up to 99% of viruses and bacteria**. "

*Irradiance limited to 10W/m2 at 2m from the floor.

**According to two independent studies quoted in this article.

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High performance Horticulture lighting with LinearZ LED Modules

LinearZ LED Modules for horticultureGrowing plants in closed and fully controlled environments, under artificial lighting is method of growing popularity, with increasing competition to have results at a low cost and as fast as possible. Thus the lighting system plays a crucial role.

Below you will find a quick guide how to build the most efficient lighting system.

1) Research, research

Discover what spectrum and intensity of light your plants need.

You can start by reading our detailed article about horticulture lighting here

2) Choose the right PPFD and light color for your plants

By using the latest technology, special or full spectrum white light LEDs have become the most efficient and cost effective light sources for plant growth. 

With our Nichia 757 Rsp0a LEDs with white light for special spectrum for plant growth or full spectrum Nichia Optisolis CRI98 LEDs your plants will grow up to 50% more than conventional light, including standard white LEDs, a combination of red and blue LEDs or a fluorescent tube, for lower energy consumption.

With 3000K white color temperature you will have more pleasant looking plants while with 5000K you obtain faster growth.

Nichia LED for Horticulture

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Plant growth (Horticulture) lighting guide with LEDs

Light for plant growth

Industrial scale indoor agriculture under artificial lighting in closed and fully controlled environments could become the main factor that keeps at bay famine and related conflicts. With increasing population, diminishing area of agricultural land, pollution, global warming and migration to grow plants in a reliable, predictable and efficient way will become even more important in the future. For this reason it is important to understand and corectly apply the concepts of lighting for plant growth and development.

Concepts related to Horticulture lighting

A key factor in the success of indoor plant growth is the efficiency of the lighting system compared with sunlight, in the process of plant growth.

Plants grow via a process called Photosynthesis that converts electromagnetic radiation (light) into the chemical energy needed for growth and development. The other ingredients required are carbon dioxide (CO2), nutrients and water. 

Photosynthesis and PAR radiation

The electromagnetic radiation required for Photosynthesis is defined as photosynthetically active radiation (PAR) and 400 to 700 nanometers has spectral range. Only radiation in this interval can be used by photosynthetic organisms in the process of photosynthesis, to fix the carbon in CO2 into carbohydrates.

Electromagnetic radiation called visible light or simply light for a typical human eye has a spectral range from about 380 to 740 nanometers.

A common unit of measurement for Photosynthetically active radiation PAR is the photosynthetic photon flux (PPF in short), measured in units of moles per second. For many practical applications this unit is extended to PPFD, units of moles per second per square meter.

The theory behind PPF is that every absorbed photon, regardless of its wavelength and energy, has an equal contribution to the photosynthetic process. As in accordance with the Stark-Einstein law, every photon (or quantum) that is absorbed will excite one electron, regardless of the photon’s energy, between 400 nm and 700 nm. 

However, only some of photons are absorbed by a plant leaf, as determined by its optical properties and the concentration of plant pigments. The pigments are Chlorophyll A, Chlorophyll B, and Carotenoids (a/-Carotene, Lycopene, Xanthophyll).

The Chlorophylls A and B give plant leaves the characteristic green color because they reflect most of the radiation between 500 and 600 nanometres.  Plants Where more Carotenoids than Chlorophylls are present plant leaves reflect wavelengths beyond 540nm and have yellow, orange, and red colors. This includes autumn leaves when Chlorophylls have dried away. 

The graph below shows the typical absorptance spectra for Chlorophyll A, Chlorophyll B and Chlorophyll (beta-carotene). Each are explained briefly afterwards:

 Typical absorptance spectra for Chlorophyll A, Chlorophyll B and Chlorophyll (beta-carotene).

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Recommended light levels for office lighting

Recommended light levels for different types of work spaces are indicated below:

According to the standard EN 12464 Light and lighting - Lighting of workplaces -Indoor work places, the light level recommended for office work is the range 500 - 1000 lux - depending on activity. For precision and detailed works the light level may even approach 1500 - 2000 lux. For ambient lighting the minimum illuminance is 50 ulx for walls and 30 lux for ceilings.

Recommended light levels for different types of work spaces are indicated below:

(lx, lumen/m2)
Areas with traffic and corridors - stairways, escalators - lifts - storage spaces 100
Working areas where visual tasks are only occasionally performed 100 - 150
Warehouses, archives, loading bays 150
Coffee break room, technical facilities, ball-mill areas, pulp plants, waiting rooms 200
Easy office work 250
Normal office work, PC work, show rooms, laboratories, check-out areas, kitchens, auditoriums 500
Mechanical workshops, office landscapes 750
Normal drawing work, detailed mechanical workshops, operation theaters 1000
Detailed drawing work, very detailed mechanical works, electronic workshops, testing and adjustments 1500 - 2000
Performance of visual tasks of low contrast  and very small size for prolonged periods of time 2000 - 5000
Performance of very prolonged and exacting visual tasks  5000 - 10000
Performance of very special visual tasks of extremely low contrast and small size 10000 - 20000

Read more about recommended lighting levels for the home in our blog article.

Flexible LED strips for applications with high lux requirement

Recommended color rendering index CRI base on your project

The CRI, colour rendering index, is a one-number quantification that indicates the performance of an artificial light source in terms of colour rendering compared to a reference standard light source modelled on daylight. The highest number is 100, for daylight and incandescent/halogen lamps, while gas discharge lamps range from 17 to 96, with even a negative value for low sodium pressure (the yellow type used in street lamps).

Due to this variation in the ability to reproduce colour with the white light emitted by the many types of gas lamps on the market, CRI index was introduced in 1974 by the International Commission on Illumination (CIE). 

Today, with more than 40 years of use, the CRI index is firmly rooted in the lighting industry and among professionals. However, it has not been very well understood by the public. The reason was that such knowledge was not really useful as most lamps were built for specific applications that required a minimum CRI value, so one could not go wrong when choosing a lamp.

For example, for office or other linear lighting, the lamps of choice where Tri-Phospor linear fluorescent tubes on the market since the 1970s, all with a CRI value above 80. For domestic lighting, there was a mix between incandescent and halogen lamps, both with CRI100, for retail and other high intensity spot lighting, metal halide lamps with CRI min 85. Street lighting was reserved for high intensity and very efficient sodium vapour lamps, which had a poor CRI but this was considered not important.

From the year 2000 this changed with LED technology, the first light source that can be used for any application while having a broad performance and quality level, including the ability to reproduce colours accurately. It is therefore essential that you choose LEDs with the right CRI level for your application.

CRI comparison

The picture above shows how colors can look different based on the CRI of the light source that illuminates them. A vibrant red under sunlight or a high CRI light can look dull or even orange under a low CRI light.

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Tips on how to build the best lines of light or linear light fixtures with LED strips

Lines of light are a new trend in lighting design and are usually made with an LED strip inside an aluminum profile that has a translucent white cover. The attraction of using such a linear light fixture is that it can be personalized. You can choose as you desire the pattern, place of installation, length (up to many meters), geometric shape or a combination of these elements.  

Line of Light with LED strip inside a profileBecause of their way of construction lines of light are a type of direct lighting. Compared with coves that are indirect lighting, lines of light are more energy efficient but can have greatly increased glare. For this reason lines of light should be designed with care and almost always be dimmable. 

Let's see how we can achieve the best results with lines of light.

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