Why the SPF Scale On Sunscreen Is Stupid
Ninety percent of skin ageing is due to the effects of the sun! Photo ageing occurs on the most exposed parts of the body - the face, neck and the back of the hands.
I am passionate about photobiology so sunscreen is one of my favourite topics and the foundation of good skincare. Look at these two twins below - the twin on the right had far more sun exposure and thus had more pronounced photo-ageing.
Or take a look at this truck driver who had one side of his face show more photo-ageing given he exposed one of the sides of his face more in the sun.
If you live in Australia you'll have to work extra hard to protect yourself from the sun because the southern hemisphere locations receive about 15% more UV radiation than the equivalent northern latitude location in any given year.
There are so many different types of sunscreen on the market - before diving into what these are, you will need to understand UV rays.
- UVA: Around 95% of UV radiation reaching the surface of our skin is UVA which is responsible for most of our photo ageing (including wrinkling and age spots).
- UVB: Whereas only 5% of UV is UVB yet scientists focused on UVB for many years because UBV is largely responsible for skin cancer and melanoma (however UVA also contributes to skin cancer too).
- UVC: UVC rays, the shortest, are considered harmless, since most UVC light is absorbed by ozone in the upper atmosphere and thus does not reach the earth.
When everyone looks at sunscreen they look at SPF (Sun Protection Factor) - they are missing their level of protection from UVA because SPF only measures protection against UVB. This is why the SPF scale on sunscreen is stupid. SPF is not a consumer-friendly number - when you buy SPF 30 it is not twice as good as SPF15.
In this blog post - there are two things I want you to takeaway:
- UVA PROTECTION REQUIRES PHYSICAL SUNSCREEN
- UVB PROTECTION REQUIRES CHEMICAL SUNSCREEN
Your traditional chemical sunscreens provide inadequate protection against UVA. This is why physical sunscreens are particularly pertinent to good skincare.
You're probably familiar with that thick, white slick of sunscreen that nobody is friends with. Yep, that tends to be physical sunscreen.
The main ingredients in physical sunscreen is zinc oxide and titanium oxide. This is what gives us a translucent, almost ghost-like appearance. This ghost-like appearance is a huge barrier to their daily usage by the public. No one wants a white film on their face everyday.
Physical sunscreens are rapidly changing. Many physical sunscreens is that today they have made them more "cosmetically elegant" through reducing the size of the zinc oxide and titanium oxide particles.
One of the cons of physical sunscreens is that they are generally more expensive than chemical sunscreens! But the more beautiful your skin is - the less skin cancer surgery and botox you will consider later on!