What does SPF mean?
SPF means ‘sun protection factor’. So the higher the number on a sunscreen bottle, the more protection you’ll get from wearing it. The SPF rating is a measure of the sunscreen’s protection against ultraviolet B (UVB) rays that cause sunburn.
What about the little stars on the bottle?
SPF measures protection against UVB rays, but there’s another type of sunbeam we need to be aware of when protecting our skin: UVA rays. The UVA protection rating on sunscreen is indicated using a star rating out of five. Look out for this too when choosing your sunscreen.
What’s the difference between UVAs and UVBs?
About 95% of light that reaches our skin is made up of UVA rays, they’re present all the time, even on cloudy days. They are what causes your skin to tan, and wrinkle, and they penetrate all the way down into the deepest layers of your skin.
UVB rays are the kind that cause visible, and painful, sunburn on the outer layers of your skin. They have a smaller wavelength to UVA rays and therefore do not penetrate as deeply. The intensity of UVB rays varies dependent on location, time of day and season. In the UK UVB rays are the strongest during our summer months, between April and October.
What if it’s cloudy?
The sun’s rays penetrate clouds easily, and UVA rays penetrate glass too, so it’s always important to use sun protection, even if it doesn’t feel like a typical sunny day. Sunlight also bounces off reflective surfaces like water, snow or sand, which is why it’s important for skiers to wear sunscreen, even when it’s snowing.
So what level of protection do I need?
The NHS recommend using an SPF of at least 30 and a UVA protection of at least four stars. Don’t forget, sunshine in small doses can be very good for us as it provides us with much needed vitamin D. Try to find a balance between enjoying the weather and protecting your skin, and remember to stay indoors or seek shade when the sun is highest in the sky, between 11am - 3pm.
