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Tuesday, August 30, 2011

Sunblock 101

As many of you head to the beach for the last hurrah of Summer, don't forget the sunblock!  Here's a helpful rundown of this must-have part of your skin care routine. . .

What's the difference between UVA & UVB rays?

Photoaging - as opposed to normal temporal aging - is due to exposure to the sun’s radiation. These rays, UVA/UVB, (280-400nml on the spectrum) are from the ultraviolet portion of the light spectrum.

UVB (short length) rays penetrate just into the epidermis.  They were once thought to be the culprits in the affect on the epidermis, but UVA (long length) rays, which penetrate deeply through the body are now known to be equally if not more damaging.  Many lines of evidence indicate that the primary biological actions of UVA radiation involve DNA damage.

UVB emissions from the sun undergo significant seasonal variations; the UVA emissions, however, do not appreciably change over the course of the year. The amount of solar UVA reaching the earth's surface is much greater than that of UVB. Also, UVA is transmitted by most window glass and many plastics that do not transmit UVB.

What can happen if I don't use adequate sunblock?

Photoaging of your skin with fine lines, wrinkles, dilated pores, laxity and sagging of skin are the direct result of sun damage to the underlying collagen and elastin fibers. Hyperpigmentation can be caused or exacerbated by the sun’s stimulation of the melanocytes, causing over-production of melanin resulting in freckles, and/or reddish hyperpigmented areas.  Damage to the skin’s vasculature can result in telangectasias (broken blood vessels).  Finally, enough exposure to the sun's damaging rays can result in formation of pre-cancerous and cancerous lesions.

Sunscreens use a variety of ingredients to protect your skin.  There are chemicals that “absorb” the sun's rays, and there are physical blockers.  SPF ratings only apply to UVB, as UVA protection cannot be measured, since the chemicals are destroyed by the rays and the air.  Thus the need for broad spectrum coverage.  So make sure your sunscreen protects from both UVB and UVA.

As to the amount of protection needed:

SPF Rating       Amount Blocked
SPF 2                           50%
SPF 4                           75%
SPF 10                        90%
SPF 30                        96.67%
SPF 50                        98%
SPF 70                        98.57
SPF 100                      99%

No sunscreen product blocks all UV rays.  So use a good broad spectrum sunblock as directed, and try to minimize your exposure to the sun between the hours of 10 a.m. and 3 p.m.  Sun responsibly - your skin will thank you for it!

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