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Time is Money

Before we can compare costs associated with a UV-C room disinfection, it is imperative we understand the steps that must be taken in order to ensure the correct dosage of UV-C on all high-touch surfaces. While highly effective in the inactivation of harmful bacteria, UV-C disinfection has two significant limitations – SHADOW (Fig.1) and DISTANCE TO SURFACE 


(Fig.2). These limitations are governed by fundamental laws of physics. Therefore, it is critical to reposition all UV-C devices to compensate for these limitations. Failure to do so could result in a substandard level of disinfection, putting patients and employees at risk of infection from harmful bacteria. The simple rule of thumb is the more disinfection positions that are applied, the better the disinfection result.

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Fig. 1 - Light travels in a straight line, objects in a path of light will cast a shadow.
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Fig. 2 - The inverse square law governs light intensity. 

In the single patient room example below, a minimum of five positions (four in the patient room, one in the bathroom) would be required to perform a correct UV-C disinfection (Fig. 3). Less than five positions would not eliminate all SHADOW and DISTANCE TO SURFACE limitations (Fig. 4). Logically, as the room size increases so must the number of disinfection positions.

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Fig. 3 - A minimum of 5 positions ensuring optimal results.
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Fig. 4 - Insufficient positions will result in substandard disinfection

Disinfection With UV-C Light - The Labor Workflow Comparison

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*Although radiating from a distance of 1 meter for 5 minutes is sufficiently long enough to inactivate most organisms, radiating from a distance of 2 meters reduces intensity to only 25%.


Unlike the UVD Robot, manual UV-C devices are switched off during repositioning and therefore, they are not disinfecting. With only 4 positions in the patient room there will be surfaces that are 2 meters away.


The accumulated UV-C energy at 2 meters distance for 5 minutes is identical to the accumulated UV-C energy at 1 meter distance for only 1 minute and 15 seconds. Therefore, a minimum radiation time of 10 minutes from each position to compensate for distance limitations (the inverse square law) is recommended.

According to the U.S. Bureau of Labor Statistics, janitors and building cleaners earn a median pay of $13.19 per hour, or $27,430 per year. This equates to a weekly rate of $494.63 based on a 37.5 hour work week.  At $13.19 per hour, this further breaks down to a $0.22 rate per minute.


As we know the labor per minute cost and the number of labor minutes required for a correct UV-C room disinfection, we can expand our comparison chart even further.

You will want to put your UV-C device to work as often as possible as infections will not be prevented by devices held in storage. With that in mind, let’s looks at the total labor costs involved with 10 room disinfections per day, 365 days per year, for 5 years.


In March 2019, a leading NHS hospital performed something never seen before in Infection Control – The full disinfection of a 21,527 Square foot outpatient Oncology department in a staggering 90 minutes. Even more impressive was the fact that this disinfection required minimal labor.

In comparison, two weeks previous, the very same disinfection was performed with a manual UV-C device. This took 20 hours of labor to complete. The disinfection plan created by the UVD Robot  (see above) was based on the manual plan with the exception that, the UVD Robot was also disinfecting while atonomously repositioning itself.

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