We first must know about UVA, UVB and UVC before we talk about the differences.
UV stands for "ultraviolet" radiation.
UVA is around us every day; it can even penetrate through window glass. We always want to look tan during summer and this is the ray that does that. UVA does tanning effect aka darken our complexion. It leads to aging and loss of collagen over long period of time because it can penetrate deeper and damage our cells.
UVB leads to sun burn, skin reddening and the main cause of skin cancer. It tends to damage our epidermal layers. UVB rays do not significantly penetrate glass.
UVC is absorbed by the ozone layer and does not reach the Earth because it has a shorter ray. Basically you can ignore UVC, I only wrote UVC because it seemed cool.
If you can't memorize don't worry. Just remember "A" in UVA stands for "Aging" and "B" in UVB stands for "Burning".
Next thing we need to know is SPF.
SPF is know as "Sun Protection Factor". It is a measurement of how well a sunscreen will protect skin from UVB rays which will damage our skin.
So what does the SPF number is about?
SPF30 means you could be out in the sun approximately *300 minutes before you get sunburned than you would be able to if you went out without. The higher the number, the longevity. However I still recommend to reapply every couple of hours.
*A user can determine how long their sunscreen will be effective by multiplying the SPF factor by the length of time it takes for him or her to suffer a burn without sunscreen.
What is Sunscreen?
Sunscreen is the chemical protection that penetrates the skin and absorbs the UVA rays before they are able to reach and damage your dermal layer. It filters the suns UV rays, keeping most rays out, but letting some in.
Sun screen helps you to tan without damaging your skin and you have to reapply every two hours and put on a lot for it to be effective because ingredients will break down after exposure in the sun.
What is Sunblock?
Sunblock is the physical protection that sits on top of the skin acting as a barrier between your skin and damaging UV rays by reflecting or absorb the rays, preventing them from penetrating into the skin.
Sun block is the opaque lotion. You can see people wearing especially at the beach, with streak of sunblock on their noses and other parts of their face. I do that to whole of my face and made myself looked like a clown.
Sunblock does not have to be reapplied every few hours. Personally I do because it wears off especially I do a lot of sports. Better be prepared right?
In fact, many brands today are a hybrid of sunscreen and sunblock. There's a way to tell whether the sunscreen offers UVA protection is by the word "Broad Spectrum". Without it, it's just an average sunscreen.
What is PA+++?
PA means "Protection Grade of UVA". PA followed by plus signs is a designation used in Japan to rate the UVA protection of a sunscreen. The number of "+" symbols after "PA" indicate the level of UVA protection; PA+ means some UVA protection. In fact "PA" equals to "Broad Spectrum".
Take care of your skin! Have fun in the sun!
Original Post: https://suzanneworld.wordpress.com/2016/04/23/differences-in-s…en-and-sun-block/