There is energy moving in waves all around you. You cannot see, touch or feel these waves but they are essential to your everyday life. Every time you turn on the radio, use wif-fi or your cell phone you are tapping into invisible electromagnetic energy that travels in waves. Electromagnetic waves go from very long (radio waves), to very short (gamma rays). Some of these rays, especially the ones on the shorter end, can be very damaging for your health.
Ultraviolet (UV) energy is practically invisible to the naked eye. It is located at the very edge of the visible light spectrum (as soon as we enter the light spectrum we encounter the notorious blue light). UV is divided into three parts depending on its range of wavelengths. UVA is 290-320nm, UVB 320-400 nm and UVC 100-290 nm. UVC is of no concern to us, as it is completely filtered out by our ozone layer.
UVB makes up 5-10% of UV radiation and is the primary cause of sunburn. It penetrates the top levels of the skin’s layers, stimulating the skin to produce more melanin and thicker epidermis, which is what we recognize as a tan.
UVA makes up 90- 95% of UV radiation is the primary cause of long term skin damage including loss of elasticity and wrinkling. It penetrates much deeper into the skin than UVB and its effects are seen much later compared to the immediate inflammatory effects of UVB. UVA can create reactive oxygen species (highly reactive chemicals created by O2) that can indirectly damage our DNA.
Both UVA and UVB play a role in skin damage and the formation of skin cancer. It is fundamental to protect yourself from both UVA & UVB for real sun protection.
When a UV filter blocks both UVB and UVA it is full spectrum protection.
It has been suggested that using sunscreens that only block UVB light may actually increase the risk of skin cancer. This is because sunscreens that only block UVB radiation are blocking out the 5 -10 % of the UV radiation that you are exposing yourself to, while at the same time stopping your skin from burning and allowing you to dangerously over-expose yourself to the 90 - 95% of UVA radiation without realizing it. When you block UVB you prevent skin inflammation and sunburn, nature's warning sign that your skin is being badly damaged and that you should get out of the sun. You could think of UVB sun filters like pain killers that remove the symptoms without addressing the cause of the discomfort.
Many chemical (organic) filters do not block both UVA and UVB and must be combined to create a sunscreen that offers full protection. In terms of mineral filters, titanium dioxide is very good at blocking UVB, but not so great at blocking UVA’s. Zinc oxide is number one, naturally blocking both UVA and UVB light.
Whenever choosing a sunscreen it is not only important to look at the UV filters used but if the product is declared to be broad spectrum protection. Otherwise, you risk doing exactly what you didn't want to do, that is, overexposing and damaging your skin with harmful UV radiation.