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BonPills: curiosities about sunscreens

Like every Thursday we are at a new episode of BonPills! Today we thought of two other curiosities about solar to close the circle and have a complete overview, by now you too are experts in the field!

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The sun protection value, universally recognized as SPF is a numerical value that indicates the level of protection against solar radiation of a cosmetic product, the higher this number is, the greater the sun protection.

This value is measured through a in vivo test (carried out on people) which measures the minimum dose of solar radiation capable of inducing erythema on the skin exposed to UVB rays with the sunscreen applied and without the sunscreen applied.

If exposing yourself to the sun without applying sunscreen the erythema appears after about 15 minutes, using for example an SPF 30 product, the skin will start to redden no longer after just 15 minutes but after 450 minutes, a value that is obtained by multiplying the canonical 15 minutes of the onset of the erythema and the value of SPF, in this case 30 (5x30 = 450). Therefore, by applying a sunscreen with a protection factor SPF 30 , the rash will appear after about 7 hours and 50 minutes.

On the other hand, for example, with a sunscreen with SPF10 protection, during the experiment, sunburn will show up after 150 minutes (15x10 = 150) and therefore after 2 and a half hours.

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A solar product is often stressed and is destined to be subjected to extreme conditions for several hours such as heat, salt, water, high temperatures , it is often not even closed properly and some sand particles can get inside the product.

Pto guarantee the effectiveness of the sunscreen, sunscreens from the previous year should not be used. Indeed, products of this kind usually have a PAO (Period After Opening) which varies from 6 to 8 months, therefore after six months after opening a sunscreen loses its effectiveness, it no longer protects against the sun's rays and must be thrown away. 

Federica Cosmast

Dott.ssa Federica D'Incà - COSMAST Master in Cosmetic Science and Technology

"Every woman has the right to be beautiful" - Elizabeth Arden

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