SPF in Sunscreen – The Basics

SPF stands for ‘sun protection factor’. Basically, the SPF in sunscreen protects your skin from cancer-causing UV rays by multiplying your natural defense against the rays. It sounds confusing, but it is not. Here’s how it works: If you burn easily and can usually only last 10 minutes in the sun, a sunscreen with SPF 15 will theoretically protect you 15 times longer than your natural protection time, so in this case you’ll be protected against UV rays. for 150 minutes. However, that is a theoretical time, it does not take into account sweating, swimming or wearing clothes, or any other factor that may remove sunscreen or impede its benefits.

Another thing to keep in mind is that once you’ve used up your protection time (the theoretical 150 minutes), another dose of sunscreen won’t add any more protection for that day. In this case, if you’ve been outside in the sun during your ‘protected’ time minutes, it’s best to avoid the sun for at least the rest of the day to avoid getting burned.

On the subject of sunburn, there are 2 types of UV (ultraviolet) rays that can cause cancer: UVA and UVB.

UVA rays are the sun’s rays that cause our skin to tan and wrinkle and over time will cause age spots and sagging skin. Although not as powerful as UVB rays, it can penetrate deeper into the skin. UVB are shorter and more powerful ultraviolet radiation from sunlight. UVB rays are responsible for sunburn: they affect the outer layer of the skin (epidermis) and contribute significantly to the development of skin cancer. The best sunscreens protect from UVA and UVB rays.

Different parts of the world have varying burn times depending on how strong the ozone layer is in that part of the world. New Zealand, for example, has a “hole” in it and recording times can be very fast.