Have there been any positive public health effects due to UV lights?

Question

Occasionally, in hospitals and in eating establishments in the US, they have industrial grade UV lights in sconces attached to the wall (though they seem to be less prominent as the years go by). I understand the anti-microbial properties of UV light, but are these devices anything more than show pieces? Have there been any lasting, significant public health gains that have been correlated with the use of UV light in public places?

Answer 1

Hello,

In principle shortwave UV is considered lethal to microorganisms and more importantly inactivates DNA due to the accumulations of thymine dimers. There are several caveats on to this working optimally not the least of which is whether you are dealing with photo-insensitive microorganisms, intensity of light source, distance of light source, augmentation with photosensitizers, etc. UV treatment is a tool as part of a process. A researcher/company might use several tools in combination to decontaminate a bench, room, etc. For example,

1) treatment with 70% ethanol

2) 30 minute UV exposure

or

1) treatment with 70% ethanol

2) treatment with 10% bleach

3) 30 minute UV exposure

or

1) treatment with 70% ethanol

2) treatment with 10% bleach

3) 30 minute UV exposure + photosensitizers

The UV light is not show. You can find examples of this being used effectively (see references in reference 1 below). It comes down to how the UV light is implemented. Because users may use the UV strategy in difference ways, you will get different outcomes. In a recent literature review, researchers cannot conclude the efficacy of UV light treatment for these exact reasons let alone make predictions about public health outcomes on a wholistic scale. It's not to say it doesn't work, it's just that we don't have a uniform protocol that everyone follows. Hope this helps. See suggested reading below.

References:

1) Health Quality Ontario (2018) Portable UV light surface-disinfecting devices for prevention of HAI: a health technology assessment

2) Reed (2010) The history of UV germicidal irradiation for air disinfection