The SPF rating of Car windshields

Who_are_you · 27th May 2018, 08:27

By law, windshields must be made of laminated glass, which means they're formed from three parts: two 2.1-millimeter layers of glass separated by an 0.8-millimeter piece of stretchy plastic. The glass is made to break easily if something - the driver's head, for example, or a deer - comes in contact with it. The plastic then stretches to absorb that impact.

The layer of plastic helps windshields absorb nearly all of the sun's ultraviolet rays. Plastic is naturally good at absorbing UV rays, Dishart says, and can be made with extra UV absorbers to protect even more. He says windshields absorb 100 percent of UVB rays, which cause sunburn, and around 98 percent of UVA rays, which don't cause sunburn but can do long-term damage to the skin.

That gives windshields a sun protection factor - or SPF - of 50 or more, the equivalent of some of the strongest sunscreens, Dishart said.

Sunroofs, too, often contain UV-absorbing technology that can block around 90 percent of UV rays. That's partly to keep the car cool as well as protect occupants from sun exposure.

But side and rear windows are a different story, and their SPF can vary a lot depending on the vehicle.

Side windows are usually made from cheaper tempered glass, which is around 4 millimeters thick and doesn't include a layer of plastic. Tempered glass is designed to shatter into tiny pieces, to protect the occupants in a crash. But unless they're tinted for privacy, side windows usually absorb only 65 percent of UV rays. That gives them an SPF of around 16, Dishart says, the same as some of the lowest grades of sunscreen.

Source : http://www.tampabay.com/news/health/...he-sun/2139733

Thad E Ginathom · 27th May 2018, 19:26

The report was written and published in America. Does the same thing apply here in India?

Yes, indeed, our windscreens are laminated; it would be incredibly dangerous if they were not, but is there any law about UV rejection, and do all or most Indian windscreens do it?

alpha1 · 28th May 2018, 11:42

Quote:

Originally Posted by Thad E Ginathom

The report was written and published in America. Does the same thing apply here in India?

Yes, indeed, our windscreens are laminated; it would be incredibly dangerous if they were not, but is there any law about UV rejection, and do all or most Indian windscreens do it?

Even in the US:

Quote:

But there are no requirements for sun protection. That can vary by vehicle, and even by window within a vehicle.

So ... the UV protection is mainly a side effect of using laminated glasses, and no one knows how much protection it actually offers - since it is not by intended design.

Actually this gives me an idea: manufacturers should make glass comply with certain SPF, PA etc testing norms and market it actively.

RacerByHeart · 30th May 2018, 14:57

Thanks for providing this information. I am sensitive to UV. I can not tolerate the sun for more than 15 minutes. Skin becomes itchy and starts burning. But I can easily drive upto 30 mins. I knew that the car glasses cut the UV, but did not know how much.

27th May 2018, 08:27	#1
Who_are_you BHPian Join Date: Apr 2018 Location: Pune Posts: 172 Thanked: 421 Times	The SPF rating of Car windshields By law, windshields must be made of laminated glass, which means they're formed from three parts: two 2.1-millimeter layers of glass separated by an 0.8-millimeter piece of stretchy plastic. The glass is made to break easily if something - the driver's head, for example, or a deer - comes in contact with it. The plastic then stretches to absorb that impact. The layer of plastic helps windshields absorb nearly all of the sun's ultraviolet rays. Plastic is naturally good at absorbing UV rays, Dishart says, and can be made with extra UV absorbers to protect even more. He says windshields absorb 100 percent of UVB rays, which cause sunburn, and around 98 percent of UVA rays, which don't cause sunburn but can do long-term damage to the skin. That gives windshields a sun protection factor - or SPF - of 50 or more, the equivalent of some of the strongest sunscreens, Dishart said. Sunroofs, too, often contain UV-absorbing technology that can block around 90 percent of UV rays. That's partly to keep the car cool as well as protect occupants from sun exposure. But side and rear windows are a different story, and their SPF can vary a lot depending on the vehicle. Side windows are usually made from cheaper tempered glass, which is around 4 millimeters thick and doesn't include a layer of plastic. Tempered glass is designed to shatter into tiny pieces, to protect the occupants in a crash. But unless they're tinted for privacy, side windows usually absorb only 65 percent of UV rays. That gives them an SPF of around 16, Dishart says, the same as some of the lowest grades of sunscreen. Source : http://www.tampabay.com/news/health/...he-sun/2139733 Last edited by Aditya : 28th May 2018 at 09:38. Reason: Formatting
	(10) Thanks

27th May 2018, 19:26	#2
Thad E Ginathom Distinguished - BHPian Join Date: Jun 2007 Location: Chennai Posts: 11,002 Thanked: 26,425 Times	re: The SPF rating of Car windshields The report was written and published in America. Does the same thing apply here in India? Yes, indeed, our windscreens are laminated; it would be incredibly dangerous if they were not, but is there any law about UV rejection, and do all or most Indian windscreens do it?
	(1) Thanks

30th May 2018, 14:57	#4
RacerByHeart BHPian Join Date: Jun 2008 Location: Doha/Bangalore Posts: 42 Thanked: 32 Times	Re: The SPF rating of Car windshields Thanks for providing this information. I am sensitive to UV. I can not tolerate the sun for more than 15 minutes. Skin becomes itchy and starts burning. But I can easily drive upto 30 mins. I knew that the car glasses cut the UV, but did not know how much.
	() Thanks