SPF, UVA/UVB and the 'UVA in a circle' symbol
Sun protection labels are full of numbers and symbols: an SPF value, words such as 'high protection', and sometimes the letters 'UVA' inside a circle. This guide explains what SPF actually measures, the difference between UVA and UVB rays, and what the 'UVA in a circle' symbol means in relation to the European Commission's recommendation on sunscreens. With this you can read a label with confidence. This is general information — always follow the instructions on the product itself.
UVA and UVB — what is the difference
Sunlight reaches the skin as two types of ultraviolet radiation. UVB rays act mainly on the surface of the skin and are the main cause of sunburn (erythema). UVA rays have a longer wavelength, penetrate more deeply and are strongly linked to premature skin ageing; both UVA and UVB contribute to skin damage and to the longer-term risks of UV exposure. Good sun protection therefore has to address both — this is what the term 'broad spectrum' refers to.
What SPF means
SPF stands for Sun Protection Factor. It measures how well a product protects against UVB radiation — that is, against sunburn — and is not a measure of how long you can stay in the sun. The scale is not linear: SPF 15 filters roughly 93% of UVB, SPF 30 about 97% and SPF 50 about 98%, so no product blocks 100%. How much protection you actually get also depends on applying enough product and reapplying it regularly.
Protection categories
Under Commission Recommendation 2006/647/EC, sunscreen protection is grouped into four categories, each shown on the label together with the SPF number: - Low protection: SPF 6 and 10 - Medium protection: SPF 15, 20 and 25 - High protection: SPF 30 and 50 - Very high protection: SPF 50+ The recommendation sets a minimum SPF of 6 for a product to count as a sunscreen. Showing the category next to the number makes it easier to compare products at a glance.
The 'UVA in a circle' symbol
The 'UVA in a circle' symbol — the letters UVA inside a circle — was introduced by the European cosmetics industry (Cosmetics Europe, formerly COLIPA) as a marker of compliance. It signals that a product meets the UVA criteria of Commission Recommendation 2006/647/EC: its UVA protection factor is at least one third (1/3) of the labelled SPF and its critical wavelength is at least 370 nm. In practice this means the UVA protection rises in proportion to the SPF: the higher the SPF you choose, the more UVA protection the symbol guarantees. Spotting this symbol is a quick way to confirm balanced UVA and UVB protection.
How to read the label
To choose sun protection, look for three things together: the SPF number, the protection category (from low to very high) and the 'UVA in a circle' symbol for balanced UVA protection. The Commission also advises against misleading claims: sunscreens should not be described as a 'sunblock', as offering 'total' or '100%' protection, or as protecting 'all day', because no product blocks all UV radiation and every sunscreen has to be reapplied — after swimming, towelling or sweating and at regular intervals. Read the amount and timing instructions on the pack and apply generously.