Comment
Comment
I just got an E-mail from a liberal friend in Colorado Springs, wondering if there might be something to Lysol Donnie’s claim that ultraviolet light could kill microbes.
That’s the problem with propaganda, it will even penetrate a rational person’s thinking.
He can be reasoned with, unlike conservatives. Though Donnie doesn’t do logic, “ultraviolet kills microbes” is the fallacy of equivocation (all ultraviolet light is not created equal, but the claim treats it as if it is).
It also takes an order of magnitude of facts to refute a bullshyte claim.
Response to him (long, behind the hide bar):
It’s UV-C (100-280 nanometres) which kills microbes, along with extreme ultraviolet (10-121 nanometres or near X-rays, there is some overlap in terms). Both of these are produced by the sun, but are completely screened out by the ozone layer. Neither reaches the Earth’s surface.
UV-C can be created on the Earth’s surface artificially (such as tanning beds, certain city water purification systems, and EPROM erasers).
Some UV-B (280-315 nanometres) reaches the Earth’s surface, but is mostly screened out by ozone and oxygen. UV-B is what causes sunburns and cataracts. It is for that reason (cataracts) opticians now offer ultraviolet filtering for spectacles.
UV-A (315-400 nanometres) completely penetrates the atmosphere. It is the component light of a blacklight. If blacklights could kill microbes, every discothéque in the country would have been germ-free in the Seventies and Eighties.
Moreover, animals originally evolved with tetracromacy (four different types of cones to detect colours, including an ultraviolet cone). Most mammals eventually evolved to lose two of the four cones (thereby losing the ability to see light past violet in the electromagnetic spectrum).
That said, studies indicate about half of women and 8% of men are tetracromats (the genes for eye cones are carried on the X chromosome), which can be shown by people who can discern the colour indigo, and the colour of UV-A—which appears black to trichromats).
An easy way to test it for yourself if you can discern the difference Indigo is to have your computer display what is called “Web Color Indigo” (RGB code 75, 0, 130, with which I encoded the name of the colour if your E-mail client will display colours in E-mails). A tetrachromat (a person with an ultraviolet cone) will see Web Color Indigo (I did it again there) as distinct from either blue or violet. Because so many people cannot see indigo as a distinct colour, it was dropped from the original rainbow of colours named by Isaac Newton.
If any old ultraviolet light could kill microbes, then we would have no microbes (or any other life). Microbes evolved to exist in our current environment which has UV-A and UV-B.
