Archive for March, 2020

With the onset and spread of SARS-CoV-2 virus and the COVID19 it causes, I have seen many offer up the idea of using low cost UV light sources used primarily for curing resins and/or finger nail polish, as a method for sterilizing surfaces and used masks. Cutting to the chase… a $35 nail salon cure light is not going to work.

These sources use light between 365nm and 405nm, depending on the intended application. This is considered long wavelength UV light, or UVA (315 to 400nm). While these may be somewhat effective against some bacterial invasions, with extremely long exposures and/or very high intensity levels (well beyond those of a small cure light), there is no evidence this is a reliable sterilization solution for viruses.

To kill viruses, hospitals are now using UVlight robots that emit high levels of UVC radiation between 200nm and 280nm, and the primary germicidal range for UVC is between 254nm and 260nm, for periods of around 20 to 30 minutes – on top of chemical cleaning and sterilization procedures. The reason they use robots, is that this radiation is dangerous to human occupants, so is not done when anyone is in the room. UVC disrupts the DNA and RNA of micro-organisms, which prevents them from reproducing. Read Here for more on these machines and their use.

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