Peak Warming Man said:
party_pants said:
random question: do humans need UV light to tan?Say I had a nice deck chair indoors in a conservatory or greenhouse or something like that, and the glass roof blocked out most of the UV light. Could I still get a tan from sitting in that chair?
Worth a thread, I don’t know, or if it would make vitamin D.
please also note PWM’s supplementary question.
sarahs mum said:
Michael V said:
party_pants said:Yes. (I’m pretty certain.)
random question: do humans need UV light to tan?Say I had a nice deck chair indoors in a conservatory or greenhouse or something like that, and the glass roof blocked out most of the UV light. Could I still get a tan from sitting in that chair?
Probably not.
I thought uv tanned and infra red burned. But that might be myth.
Michael V said:
party_pants said:Yes. (I’m pretty certain.)
random question: do humans need UV light to tan?Say I had a nice deck chair indoors in a conservatory or greenhouse or something like that, and the glass roof blocked out most of the UV light. Could I still get a tan from sitting in that chair?
Probably not.
Solariums
Solariums (also known as sunbeds) are machines that emit ultraviolet radiation. They are not a safe way to tan and they significantly increase your risk of cancer. It is therefore illegal to operate a commercial solarium in Australia.
The levels of UV radiation emitted from solariums can be up to six times as strong as the midday summer sun. People who use a solarium before the age of 35 have a 59% greater risk of melanoma than those who do not use solariums.
http://www.sunsmart.com.au/uv-sun-protection/solariums
> Could I still get a tan from sitting in that chair?
Vehicle windows block out most but not all of the UV light. It’s been found that truck drivers who always drive with the windows up still preferentially get a tan on the side nearest the window.
party_pants said:
sarahs mum said:
Michael V said:
Yes. (I’m pretty certain.)Probably not.
I thought uv tanned and infra red burned. But that might be myth.
That’s correct.
And UV causes skin cancers, and sunburn.
This link is interesting.
https://www.tandfonline.com/doi/full/10.1080/19381980.2017.1375635
The production of vitamin D in the skin is a demonstrably positive aspect of tanning. UVA radiation from a sunbed also induces immediate pigment darkening which is not involved in vitamin D synthesis and also produces nitric oxide in the skin which leads to relaxation of blood vessels, lower blood pressure and improved cardiovascular health. There are risks to any type of UV exposure, whether from the sun or a sunbed. It is widely accepted that excessive and overexposure of UV can increase the risk of skin cancer. Squamous cell carcinoma (SCC) seems to be related to excessive UV exposure where basal cell carcinoma (BCC) and melanoma is related to intermittent exposure such as sun burning.
Ultraviolet-B (UVB) radiation initiates vitamin D synthesis, and wintertime sun exposure at northern latitudes (above 44°N) does not contain sufficient UVB radiation to stimulate vitamin D synthesis. Natural vitamin D production is limited by season depending on latitude. In fact, vitamin D production is not possible even on exposed skin for four or more months of the year depending on how far north one resides due to lack of UVB radiation. Sunlamps with a UVB component similar to solar summer output may provide an alternative during the winter.
Yes you are still getting some UV. If you’re Alex, you’ll still burn.
Since this is a thread about UV…. when Mini Me was born, she had severe jaundice. She was under the lights in hospital for a couple of days. She wore the little mask to protect her eyes but other than that, and a nappy, she was naked. I asked about the UV wavelengths and whether she would tan. The dr just looked at me funny and said no. I thought it was a cromulent question. Anyhoo, does anyone happen to know the difference of this UV as opposed to the sun’s UV?
The sunlight at ground level contains much more UVA than UVB.
Typical soda lime glass, 2 mm thick, has a transmissibility that drops to zero at about 250 nm, ie.it still lets through UVB, but less than it lets through of UVA.
https://en.m.wikipedia.org/wiki/Soda–lime_glass
mollwollfumble said:
The sunlight at ground level contains much more UVA than UVB.
Typical soda lime glass, 2 mm thick, has a transmissibility that drops to zero at about 250 nm, ie.it still lets through UVB, but less than it lets through of UVA.
https://en.m.wikipedia.org/wiki/Soda–lime_glass
At even as short a wavelength as 300 nm, in UVB, we’re still getting 90% transmittance. That surprises me greatly. In fact, I don’t think that that can be true.
mollwollfumble said:
mollwollfumble said:
The sunlight at ground level contains much more UVA than UVB.
Typical soda lime glass, 2 mm thick, has a transmissibility that drops to zero at about 250 nm, ie.it still lets through UVB, but less than it lets through of UVA.
https://en.m.wikipedia.org/wiki/Soda–lime_glass
At even as short a wavelength as 300 nm, in UVB, we’re still getting 90% transmittance. That surprises me greatly. In fact, I don’t think that that can be true.
Ah, i see, it isn’t true. That’s glass made to special optical tolerances, not standard window glass.
So what I need is a glass that blocks out UVA but allows a little UVB?
And then only suntan for small doses in my special glasshouse.
Dang, Handbook of chemistry & physics gives UV transmittance for 18 different common types of glass, but not one of them is the glass used in windows.
Anyway, on average, glass transmittance for 1 cm thick is 98.5% at 365 nm and somewhere between 35% and 50% at 310 mn.
365 nm is in the UVA range, (320 to 400 nm) good for tanning.
310 nm is in the UVB range, (280 to 320 nm) good for Vitamin D.
That’s a lot more UV transmission than I expected.
In very basic terms, glass spectacle lenses let UV through and plastic ones don’t (not complete 100% block but a lot). The basic plastic used for spectacle lenses is known as CR39 (resin batch 39 was the one that worked). We pretty much stopped using glass spectacle lenses around 20 – 25 years ago when the Yanks started suing each other for damage from broken lenses to faces in accidents. Glass shatters, CR39 breaks into blunt bits. It’s not easy to get glass lenses now.
I have no idea about window glass. Or laminated windscreens. Or any other sort of glass really.
The thing I think is interesting about that is that we have now been doing a sort of crowd experiment for 20-25 years….prior to that spectacle wearers eyes got pretty much the same UV load over a lifetime as non spectacle wearers. Since the advent of CR39, spectacle wearers have had a lot more UV protection over a lifetime. If cataract and retinal degenerations with age are truly a consequence of light and UV dose, some of us should be a lot better off than our predecessors.
:)
Most vehicle glasses (which are often the ones we get most of our sunlight through) will block UVB, but not UVA unless they’re tinted. You get sunburn and skin cancer from UVA.
More here Cancer Council Australia Factsheet – Tinted Windows.
Clear autoglass (side windows) blocks about 97% of the UVB radiation and about 37% of UVA radiation.
Laminated windscreens block all of the UVB radiation and about 80% of the UVA radiation.
Clear windscreen films can reduce the transmission of UVR further so that as much as 97% of the UVA is blocked. This depends on the quality of film used.
Clear or tinted films can also reduce the amount of UVA and UVB penetrating through the side glass. The amount of protection varies with different products.
http://www.cutyourcancerrisk.org.au/blogs/window_tinting.html
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Benefits of having your car windows tinted
We can concede that window tinting looks great, that’s a given, but here are some other reasons why we strongly feel that you should consider tinting the windows on your car.
Protect you, your family and your car’s interior from the suns harmful rays. Our tints effectively block out 99% of the suns harmful UV rays.
I got the windows tinted on the Rulemobile about 10 months ago and the difference is amazing.
it makes me wonder if getting the windscreen done with the clear sheet is worth it. the hands get blasted with UV. when you are doing long distances its the hands that get the brunt of the UV.
wookiemeister said:
it makes me wonder if getting the windscreen done with the clear sheet is worth it. the hands get blasted with UV. when you are doing long distances its the hands that get the brunt of the UV.
Yep. Lot of skin cancers on the knuckles. It’s fairly common for screen to have a tinted strip across the top (which you can get added, if yours doesn’t) but your choices would seem to be sunscreen or gloves.
Rule 303 said:
wookiemeister said:
it makes me wonder if getting the windscreen done with the clear sheet is worth it. the hands get blasted with UV. when you are doing long distances its the hands that get the brunt of the UV.
Yep. Lot of skin cancers on the knuckles. It’s fairly common for screen to have a tinted strip across the top (which you can get added, if yours doesn’t) but your choices would seem to be sunscreen or gloves.
placing a black towel across the dash helps absorb the glare that bounces into the face
wookiemeister said:
placing a black towel across the dash helps absorb the glare that bounces into the face
That’s a good idea. I’ve got the molded carpet dash mat, mostly to protect the dash, but it probably absorbs a lot of light, too.
buffy said:
In very basic terms, glass spectacle lenses let UV through and plastic ones don’t (not complete 100% block but a lot). The basic plastic used for spectacle lenses is known as CR39 (resin batch 39 was the one that worked). We pretty much stopped using glass spectacle lenses around 20 – 25 years ago when the Yanks started suing each other for damage from broken lenses to faces in accidents. Glass shatters, CR39 breaks into blunt bits. It’s not easy to get glass lenses now.
The thing I think is interesting about that is that we have now been doing a sort of crowd experiment for 20-25 years….prior to that spectacle wearers eyes got pretty much the same UV load over a lifetime as non spectacle wearers. Since the advent of CR39, spectacle wearers have had a lot more UV protection over a lifetime. If cataract and retinal degenerations with age are truly a consequence of light and UV dose, some of us should be a lot better off than our predecessors.
:)
That’s interesting.
Checks web “CR-39, or allyl diglycol carbonate, is a plastic polymer commonly used in the manufacture of eyeglass lenses. The abbreviation stands for “Columbia Resin #39”, which was the 39th formula of a thermosetting plastic developed by the Columbia Resins project in 1940.” From the spectrum below, it blocks by far the majority of UVA and all of UVB.
I’ve gone for a high refractive index lens for many years. I’ve no idea what that is made of. So I’ve probably never ever had CR-39.
Rule 303 said:
I got the windows tinted on the Rulemobile about 10 months ago and the difference is amazing.
I’ve never understood why anyone would want window tinting, or sunglasses. Useful during hangovers perhaps, but better to avoid hangovers in the first place.
I mean, the worst light conditions for discomfort and pain are badly adjusted vehicle headlights. Or driving straight into the setting sun. Or to put it another way, it’s the contrast between light and dark in the visual field that is painful, and tinting does nothing to address that. For sunglasses, the untinted light that comes in around the edges of the sunglasses, reflected off the inside of the glasses, is an extreme annoyance, even with wrap-arounds.
Even plain glass cuts out too much light and distorts the visible spectrum far too much. If I want to see beauty, the only way is to take off my glasses and go outside.
mollwollfumble said:
I’ve never understood why anyone would want window tinting, or sunglasses. Useful during hangovers perhaps, but better to avoid hangovers in the first place.
Having sunnies that block UV light is a good thing, as it helps your eyes lenses go longer without needing reading glasses. I also find the brightness of a sunny day a bit too strong for me so I typically wear sunnies all the time when outside.
Definitely needed them when flying as the tops of the white clouds can be very bright indeed. I also always wear sunnies when riding my bikes as I leave the visor on the helmet open to get cooling air in and I really don’t want to catch an insect or something-or-other in the eye.
>>Having sunnies that block UV light is a good thing, as it helps your eyes lenses go longer without needing reading glasses.<<
Sorry, incorrect.
But it might delay the development of cataract and macular changes in old age.
>>Definitely needed them when flying<< because up above the clouds and with the massive reflection from the clouds you are copping a much bigger amount of UV and visible light.
buffy said:
>>Having sunnies that block UV light is a good thing, as it helps your eyes lenses go longer without needing reading glasses.<<
Sorry, incorrect.
But it might delay the development of cataract and macular changes in old age.
Ah okay thanks for the correction. My dad had cataracts in his late 70’s/early 80’s and I really do wish to avoid getting them.
Spiny Norman said:
buffy said:>>Having sunnies that block UV light is a good thing, as it helps your eyes lenses go longer without needing reading glasses.<<
Sorry, incorrect.
But it might delay the development of cataract and macular changes in old age.
Ah okay thanks for the correction. My dad had cataracts in his late 70’s/early 80’s and I really do wish to avoid getting them.
You will almost certainly get cataract. It is an ageing effect. Embryologically speaking, the lenses in the eyes come from the same place as skin. Skin changes with the dose over lifetime of light and UV, and the lenses do the same. They are somewhat protected by the cornea. However, it is unusual not to have some cataract by the time you are 50, if we look closely for it. It won’t necessarily cause problems with your vision until later, and indeed I have some nonagenarians who have not yet had to have anything done. On the other hand, I have sent people in their 60s for surgery. Mostly it seems to affect function around the mid 70s. My trigger for sending people is if it is getting worse over a 6 month period and they are heading towards me telling them they no longer reach the driving requirements.
Something on tv the other day that I only half watching, a woman from the Cancer Council was saying that wearing UV sunnies helped protect against eye cancer (incl skin cancers around the eyes) and retinal damage from bright sunlight.
mollwollfumble said:
I mean, the worst light conditions for discomfort and pain are badly adjusted vehicle headlights. Or driving straight into the setting sun. Or to put it another way, it’s the contrast between light and dark in the visual field that is painful, and tinting does nothing to address that. For sunglasses, the untinted light that comes in around the edges of the sunglasses, reflected off the inside of the glasses, is an extreme annoyance, even with wrap-arounds.Even plain glass cuts out too much light and distorts the visible spectrum far too much. If I want to see beauty, the only way is to take off my glasses and go outside.
For starters, as already discussed, automotive glasses don’t cut down UV enough to protect your skin. There are also situations where people can spend long periods in very intense light (A truck driver who drives Sydney-Melbourne every afternoon, for example, will be exposed to intense UV through the side window for many hours a day).
I live on the Mornington peninsula, as you might recall, and the Frankston bi-pass freeway, which runs SSW – SW, has no trees for sunlight protection all the way from Skye to Rosebud. On a busy Summer afternoon, it can easily take an hour to travel that section, and it’s not unusual to see people covering their arms and faces with towels, blankets, newspapers etc to protect themselves.
If we look at the risk that presents for a white guy under UV intensity 12 sunlight, the time to burn is about 10 minutes. Looking at the large body of evidence on the long-term effects of sunburn, I think there’s more to worry about here than optical discomfort from contrast, as you seem to be suggesting above.