UV basics

[kenny1999]

Is there any study or research on approximately how much damaging or harmful UV could reach inside a room in an apartment building of a city without any UV film or curtain? It's said most harmful UV is already blocked / absorbed by the glass of windows or other obstacles before reaching inside. Is it validated? 

[swansont]

It's fairly easy to find the absorption and transmission curves for various glasses

 

You can see here that the transmission drops to basically zero between 250 nm and 300 nm. So these let UVA through but blocks some of UVB (depending on the glass), and it looks like they block all of UVC

https://www.ssi.shimadzu.com/industries/automotive-materials-testing/ceramics-glasses/measurement-of-solar-transmittance-through-plate-glass/index.html

[kenny1999]

11 hours ago, swansont said:

It's fairly easy to find the absorption and transmission curves for various glasses

 

You can see here that the transmission drops to basically zero between 250 nm and 300 nm. So these let UVA through but blocks some of UVB (depending on the glass), and it looks like they block all of UVC

https://www.ssi.shimadzu.com/industries/automotive-materials-testing/ceramics-glasses/measurement-of-solar-transmittance-through-plate-glass/index.html

I think all UVC is already blocked by the atmosphere so it is not our consideration.

Do you know, for the area which is not shined by strong sunlight directly, is there any significant UVA or UVB existing?

Edited July 21, 2022 by kenny1999

[studiot]

23 hours ago, kenny1999 said:

Is there any study or research on approximately how much damaging or harmful UV could reach inside a room in an apartment building of a city without any UV film or curtain? It's said most harmful UV is already blocked / absorbed by the glass of windows or other obstacles before reaching inside. Is it validated? 

 

9 hours ago, kenny1999 said:

I think all UVC is already blocked by the atmosphere so it is not our consideration.

Do you know, for the area which is not shined by strong sunlight directly, is there any significant UVA or UVB existing?

 

Are you taking the piss ?

I thought at first you had a serious question, but then you reject your own question.

 

The short answer is, yes there is UV around and it's not all direct sunlight, it's not even all sunlight.

And yes the subject has received intensive study from many different points of view.

 

So would you like to restate your question unequivocally so we know what you really want ?

[Phi for All]

On 7/22/2022 at 2:20 AM, studiot said:

Are you taking the piss ?

I thought at first you had a serious question, but then you reject your own question.

 

The short answer is, yes there is UV around and it's not all direct sunlight, it's not even all sunlight.

And yes the subject has received intensive study from many different points of view.

 

So would you like to restate your question unequivocally so we know what you really want ?

!

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[TheVat]

On 7/21/2022 at 4:30 PM, kenny1999 said:

 

Do you know, for the area which is not shined by strong sunlight directly, is there any significant UVA or UVB existing?

There is.  When I hike in rocky canyons around here, a broad brimmed hat that blocks direct solar rays is insufficient because UV bounces off some minerals in rock and so I get some UV from below.  A similar case is walking by water - UV will bounce off the water and come in below the brim.  This reflected UV is less than from direct sun, but it is still significant from a dermatological perspective if you are exposed for more than a few minutes.  Sand and snow also reflect quite a bit of UV.