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Atomic Structure

Nanoscience - Properties and Uses of Nanoparticles - Sunscreens.

Sunscreens are used to protect skin against the harmful effects
of UV light (ultraviolet light) from the Sun.
The wavelengths of UV light which cause skin damage
are divided into two ranges called UVA and UVB.

UVA contains the longer wavelength of UV light which can
damage cells deep inside skin tissue and lead to skin cancer.
Zinc oxide and titanium dioxide can effectively reflect UVA
 and prevent it from reaching the skin. These two compounds
are made even more effective in sunscreens when used in the
form of nanoparticles because of their high surface area.

UVB contains the shorter wavelength of UV light which causes
sunburn but is less likely to cause cancer. Some sunscreens may
be more effective at blocking either UVA or UVB but not both.

Sunscreens may also have a SPF (sun protection factor) rating.
The higher the number, the greater the protection given.
You must use care when using sunscreen to avoid being
over confident that you will have enough protection.
Read the instructions thoroughly and follow the recommendations
for re-applying the sunscreen, especially if you are swimming
as water will remove some sunscreen from the surface of the skin.

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