LD UVC About

What is UVC Light?

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Ultraviolet (UV) light is a component of the electromagnetic spectrum that falls in the region between visible light and X-rays, in the range of 100 nm to 400 nm.

100 nm to 200 nm
Far UV or vacuum UV (the wavelengths propagates only in vacuum)

200 nm to 280 nm
UVC – useful for disinfection and sensing

80 nm to 315 nm
UVB – useful for curing, tanning and medical applications

315 nm to 400 nm
UVA (or “near UV”) – useful for printing, curing, lithography, sensing and medical applications

How UVC Disinfection Works?


Because of the spectral sensitivity of DNA & RNA, it’s only the UVC region of the electromagnetic spectrum (200-280 nm) that demonstrates this germicidal property. Hence, when biological organisms are exposed to UVC, it gets absorbed by the DNA, RNA and proteins of their cells. This absorption disrupts their replication process and ruptures their cells’ walls due to which they fail to multiply.

Ensuring Complete Inactivation

Table 1 Log Reduction Value (LRV)

Disinfection is quantified by inactivation rates or Log Reduction Value (or LRV).  Log reduction is a simple mathematical term used to express the relative number of live microbes eliminated by disinfection.

UV Dose (or fluence) is the amount of UV radiation a microbe is exposed to and depends on the intensity of UV radiation and exposure time. A number of biological studies have produced widely accepted typical UV dose requirements for most commonly targeted microbes in disinfection.

1 mWs/cm2 = 1 mJ/cm2

1 milliwatt-second / square cm = 1 millijoule / square cm

UVC Dosage Chart

Incident energies of germicidal ultraviolet radiation at 253.7 nanometers necessary to inhibit colony formation in organisms (90%) and for 3-log (99.9%) reduction.

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Verifying UVC Exposure

The UVC Dose Indicator is a safe and efficient tool used to verify UVC exposure levels when using ultraviolet devices for surface disinfection. They are calibrated to indicate color changes up to 100 mJ/cm² .When exposed to UVC rays, the yellow indicator changes to orange and pink, which has been correlated to an accumulated dose sufficient to kill MRSA and C. Diff, respectively.

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UVC exposure reference chart can be used to demonstrate the color changes associated with various energy levels.

Pictures of UVC-exposed samples :

*Samples from RISE Research Institute of Sweden AB

Effectiveness of UVGI on Viruses

Top view of the UVGI solution mounted on the LD robot.

Illustration of the efficacy of the UVGI in relation to the size of the LD robot.

Based on the chart, as an example, if we need to irradiate the influenza A virus on surfaces, we would need a light energy of at least 6600 μJ/cm².

This would mean, within a radius of 1524mm, if light intensity of 24,000 μJ/cm² is dissipated constantly for 1 minute, we can destroy 99.9% of the influenza A virus.

UV Exposure (μJ/cm²) at Specified Distances

Time/radius 609mm 914mm 1524mm 3048mm
1 min 124,000 65,000 24,000 6,000
15 min 1,860,000 975,000 360,000 90,000
30 min 3,720,000 1,950,000 720,000 180,000
45 min 5,580,000 2,925,000 1,080,000 270,000
1 Hour 7,440,000 3,900,000 1,440,000 360,000
2 Hours 14,880,000 7,800,000 2,880,000 720,000

The above chart is offered as a reference point, using fresh lamps and does not account for ojects physically blocking UV ray transmission.