What is a UV Block?

Mary McMahon
Mary McMahon

A UV block is something which is capable of at least partially blocking energy in the ultraviolet area of the electromagnetic spectrum. The Sun is a notable source of UV radiation, producing a variety of wavelengths which are located within the UV range, and there are also sources such as specialized lamps which can produce light in this area of the spectrum. UV blocks are used for a wide variety of purposes.

Car windows contain UV block to protect occupants.
Car windows contain UV block to protect occupants.

Ultraviolet light can have some beneficial effects, and in fact some organisms have adapted to utilize it since it is abundantly available. However, it can also be harmful. It can cause damage to DNA, it can erode a wide variety of materials, it can cause pigments to fade, and it can simply cause a painful sunburn. For these reasons, people have developed UV blocks to use in settings where ultraviolet light is potentially dangerous or undesirable.

A UV block can partially block energy in the ultraviolet area of the electromagnetic spectrum.
A UV block can partially block energy in the ultraviolet area of the electromagnetic spectrum.

Blocks often take the form of coatings which can be applied to surfaces to provide protection. One example of such a coating is a film which can be applied to glass. These films are used on auto glass to protect components inside the car from UV damage, and in things like display windows, where prolonged exposure to sunlight causes fading over time. UV block paints are also available for coating products to provide this protection, including clear glazes which can be applied without distorting color.

Excessive exposure to ultraviolet (UV) light can damage an individual's DNA.
Excessive exposure to ultraviolet (UV) light can damage an individual's DNA.

A UV block can also be integrated into a product. Blocks can be mixed into plastics, used to impregnate fabrics, and so forth so that the product will be protected from UV radiation for life, with no concerns about a coating or film rubbing off over time. Products with integrated UV blocking tend to be more expensive because they are more costly to manufacture, although the tradeoff with a UV block is that the products will last longer than similar products which do not have UV protection.

Shade screens are another form of UV block. In this case, something with UV resistance or something which will absorb the radiation is placed between a person or object and the Sun so that ultraviolet radiation will not cause damage. Such products are adjustable, allowing users to move them with the sun and to take them down if they are no longer needed. These products can be used to control sun exposure, as for example when someone wants to tan briefly and then cover up to prevent skin damage.

Prolonged exposure to UVB rays may increase the risk of skin cancer.
Prolonged exposure to UVB rays may increase the risk of skin cancer.
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments

wizup

@Markus - I know which broadcast you're referring to. What you heard about the SPF sunblock categories is only partially right. The highest category they can read in the near future is actually fifty. There is no sufficient evidence that anything over that is any more effective.

Manufacturers are also not permitted to use the title "sunblock" anymore because there again is not enough proof that these products can totally block UV rays.

And one last thing worth mentioning from that broadcast is that the sunblock bottles can no longer state that they are waterproof or sweat-proof. They will say however "water-resistant", and for how long they protect.

People don't seem to understand that waterproof doesn't mean they're protected all day while they're running in and out of the water. For adequate protection you've got to keep applying sunscreen all day long.

Markus

Did anyone catch the news a while back about the new labeling the FDA is requiring the sunblock manufacturers to put on their products?

I caught the tail end of the story and I thought I heard them say that sunblocks over SPF 15 have no additional protection against the sun's dangerous UV rays.

Did I hear them correctly? I've always used sunblock with an SPF or at least thirty. Please share with us any knowledge you might have on this story. Thank you.

Bertrand

This I did not know. It explains why you can buy UV blocking clothing that works. I have seen it in sporting goods sections of stores. I thought it worked because it was light colored and reflected the sun's rays. I suppose that is partially true, but it also makes sense that a UV blocking product could be incorporated right into the fabric.

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