Jelight UV Sterilization and Covid-19

Background

UVC light has been used for the last 40 years for the disinfection of water, air, surfaces, and other products against viruses and bacteria. UVC light has been proven to inactivate viruses, bacteria, algae, and other protozoa from direct irradiance. The International UltraViolet Association (IUVA), has a handy fact sheet for UV disinfection on their page here (add link). As a note from their page, UVC light (200-280 nm light) in the germicidal range IS NOT THE SAME as the UVA and UVB light used in tanning beds or sunlight exposure.

What is Dosage?

Viruses and bacteria require a minimum dosage of UV light to inactivate (aka “kill”). This is typically measured in mJ/cm2 (milli Joules per square centimeter). This number is achieved when you take your intensity, typically measured in mW/cm2 (milliWatts per square centimeter) and multiply it by the exposure time. So, for example, 50 mW/cm2 over 1 second is 50 mJ/cm2 of dosage. At 2 seconds it is 100 mJ/cm2 of dosage, and so on.

Log Reduction and Determining Efficacy for Killing/Deactivation

Log reduction is most used for determining inactivation times. For example, a 1 log kill means that 90% of the bacterial population is killed in the set exposure time. Doubling the exposure time or intensity can only kill 90% of the residual 10%–so a 2 log kill is 99% and so on for 3 log (99.9%) and 4 log (99.99%) kill. Conversely, a 50% decrease in dose or exposure time decreases germicidal efficacy only from 99% to 90%. 2 log kills (99% inactivation) are frequently accepted in practice.

 

While there hasn’t been enough time for testing to be done on COVID-19 to determine the dosage needed to inactivate by 90% for a 1 log kill, UVC light has been confirmed to inactivate  other coronaviruses. Sources, linked further down the page, vary on their effective kill time due to the differences in intensities of the lamps they use to deliver the dose, lab environments, conditions on which the sample is prepared, and so on. The dose requirement in mJ, however, ranges as per the sources. One source shows the requirement for a 1 log reduction in various other coronaviruses and concludes the average dose is 67 J/m2, which is .67 mJ/cm2.3 However, other sources, such as the white paper on source 9, provide guidelines for around 40 mJ/cm2 of dosage for a 3 log kill (99.9%).9 For reference, our JUVC-5B handheld unit outputs 110 mJ/cm2 over 1 second at 2 inches away from the irradiator with our standard ozone-free lamp.

Jelight Company and our UV Machines

At Jelight Company Inc. we pride ourselves on our commitment to quality, dependability, and safety. Our handheld machines, namely the JUVC-5B, have been tested between two different radiometers* to show that the unit outputs at least 110 mW/cm2 of 254 nm intensity at 2 inches away from the irradiator. From other research done on UV disinfection, this means that our handheld can sterilize surfaces of Covid-19 as well as other bacteria and viruses as you pass over the surface.

A photo of Jelight’s JUVC-5B

We also have Youtube videos posted of the process on our Youtube Channel: 

For any inquiries, please contact us.

Our handheld units have been and are being used out in the field since 2008. Our JUVC-5B is Nationally Recognized Testing Laboratory (NRTL) listed on the OSHA website at: https://www.osha.gov/dts/otpca/nrtl/nrtllist.html. For online confirmation, the certificate can be viewed at: https://qai.org/listing-directory/ and searching by file number E10956-1801 or by company name Jelight. By extension of the QAI listing, the unit is meets the UL 61010-1 standard and CSA-C22.2 No. 61010-1-12 (R2017) standard. The unit is also CE certified.

*The 2 radiometers used for the test were: Jelight’s JEL2400 radiometer with our JXSD140T254 detector and EIT’s Power Puck II.