Three types of UV radiation are classified according to their wavelength. They differ in their biological activity and the extent to which they can penetrate the skin. Shorter the wavelengths of UV, is the more harmful radiation. UV－C is the most damaging type of UV radiation. [However, radiation of those shorter wavelength UV is prevented or minimized to reach the earth’s surface, as it is, meanwhile, filtered by the atmosphere (ozone layer).]

Both UVA and UVB, however, penetrating through atmospheric filter causes harmful effects, such as premature skin aging, eye damage (including cataracts), and skin cancers. They also suppress the immune system, reducing your ability to fight off these and other maladies.

UVA Rays: The chief cause of skin aging and wrinkling
UVB Rays: The chief cause of skin reddening and sunburn tends to damage the skin’s more superficial epidermal layers. It plays a key role in the development of skin cancer and a contributory role in tanning and photoaging.

UV-A

UVA (ultraviolet-A): UVA wavelengths deeply penetrate the dermis and subcutaneous layers of your skin. These skin layers are located beneath the epidermis, the top layer of your skin. UVAs damage collagen and elastin resulting in premature aging and wrinkling. Even though UVA rays pass the first layer of skin, where most skin cancers appear, these rays can still damage the basal and squamous cell layers of the epidermis and cause skin cancers such as basal cell carcinoma and squamous cell carcinoma.

UV-B

UVB (ultraviolet-B): UVB wavelengths don’t penetrate beyond the epidermis. These rays are 90 percent responsible for the visible redness and pain associated with sunburn. The SPF number marked on sunscreen generally indicates the UVB protection level.

UV-C

UV－C is the most damaging type of UV radiation. Currently, it is completely filtered by the ozone layer and does not reach the earth’s surface. However, it is apprehended that further depletion of ozone layer may allow some UV-C to reach the Earth’s surface in the future.

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