SPF and PA

There's just so many things human beings assume we know. We don't mean to be sarcastic at all, but to point out fact, science is still developing and even science reaches its perfection, human beings can only understand and logialize what is limited to understanding of human being - there's no beyond or beneath to it. No matter how much we try, we will never truly understand what it feels like to flap our wings to fly - nor how it feels to see a color that is outside the visible spectrum. So there are some things that we'll never possibly understand and we can't really do anything about, and then there are some things that we assume we know - how does a TV work? How does a car move? Why do airplanes fly (just think of it - it's the most heaviest chunk of iron that flies in the air!)? And these things you can come up with answers - why not feed your curiosity?

So we just wondered (almost randomly) - what truly is SPF and PA that sun block lotions give us the number of? We know they "protect" us from ultraviolet radiation (UV), and higher the number the better. But do we really know what it is?

And then we realized it was time for a micro research to share with you folks. :)

SPF stands for Sun Protection Factor (well that's a little self-explanatory huh?:P), and it decelerates the speed of skin to become burned or redden during sun exposure. The number SPF presents the time it takes your skin to burn without sun block lotion divided by the time it takes your skin to burn with sun block lotion. For example, if your skin usually becomes reddened in 15 minutes but when you use a certain sun block lotion your skin becomes burned in 4 hours, the sun block lotion has SPF of 16. (4hrs=240min, 240min/15min=16)

Because of the nature of SPF, it is said that SPF measurements of products are difficult to be accurate and precise. Time it takes a person to be sunburned varies person-by-person. In Japan, even though some products exceed SPF50, the law only permits the labeling of SPF not to exceed 50; because it's hard to be accurate. (We wonder if some products with labeling of SPF50 may possibly decelerate better - but come to think of it, we'll shower or rinse the lotion off anyways even if it decelerates forever!)

On the other hand, PA stands for Protection Grade of UVA. SPF decelerates the speed of skin reddening, while PA level presents the degree of the product preventing tanning. PA varies to PA+, PA++, PA+++, and more plus signs indicate higher level of prevention.

SPF for skin protection, and PA for beauty protection. :)

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