Two marks, two questions
Most sun protection packs sold in the United Kingdom carry at least two indications of ultraviolet A protection, and they are frequently read as if they were two versions of the same measurement. They are not.
The circled letters UVA answer a yes or no question: does this product reach a recommended minimum level of ultraviolet A protection relative to its labelled factor? The star rating answers a different question: what is the balance between this product's ultraviolet A protection and its ultraviolet B protection?
A threshold and a balance are different kinds of quantity, and conflating them produces two specific errors that appear constantly in retail description.
The circle: a threshold tied to the factor
The circled mark comes from the European Commission recommendation on the efficacy of sunscreen products and the claims made relating to them. The recommendation sets out that a product should provide ultraviolet A protection of at least one third of the labelled sun protection factor, together with a critical wavelength of at least 370 nanometres, and that a product meeting that should carry the mark.
Three properties of the mark follow from that.
It is relative, not absolute. The threshold is one third of the labelled factor, so the absolute level of ultraviolet A protection behind the mark on a factor 50 product is higher than behind the same mark on a factor 15 product. The mark looks identical in both cases.
It has no degrees. A product either meets the threshold or does not. There is no better version of the mark, and a product that comfortably exceeds the minimum carries the same circle as one that just meets it.
It comes from a recommendation. The instrument behind it is a Commission recommendation rather than a regulation, which means its status in law is different from that of a binding requirement. In practice it is the reference the industry, enforcement bodies and testing houses work to, and the general obligations of the cosmetics regime and the advertising codes do the enforcing work. That distinction is set out in the European recommendation behind the label.
The star rating: a ratio in bands
The star rating is a separate system, developed in the United Kingdom and licensed to manufacturers, that expresses the ratio between a product's mean ultraviolet A absorbance and its mean ultraviolet B absorbance. It is not a statutory requirement and it is not part of the cosmetics regulation. Products can be sold in the United Kingdom without it.
Because it is a ratio, the arithmetic behind it produces a result that catches people out. A product with a high count of stars has ultraviolet A protection that is well balanced against its ultraviolet B protection. It does not follow that the absolute ultraviolet A protection is high. A low factor product can achieve a high star count by having modest protection in both bands in a good ratio.
Put plainly: stars tell you about the shape of the protection, the factor tells you about the scale of it, and neither substitutes for the other. Reading stars as a level rather than a ratio is the single most common misreading on a British sunscreen shelf.
| Property | The circled UVA mark | The star rating |
|---|---|---|
| What it expresses | A threshold met or not met | A banded ratio between two protections |
| Relative to what | The labelled sun protection factor | The same product's own UVB protection |
| Has degrees | No | Yes, in bands |
| Statutory in the UK | Comes from a Commission recommendation, not a binding rule | No, a proprietary system used voluntarily |
| Tells you absolute UVA protection | No | No |
Framework of this publication. It describes how published rules and guidance fit together and is not a measurement, a survey or a study.
Why ultraviolet A needed its own mark at all
The reason two marks exist rather than one is a consequence of how the sun protection factor is measured. Reddening is driven predominantly by the shorter ultraviolet wavelengths, so a formulation weighted towards filters that absorb strongly in that part of the band will produce a high factor efficiently. Nothing in the test rewards absorbance further along the band, because further along the band contributes comparatively little to the endpoint being measured.
That creates a straightforward commercial incentive, and the incentive points in an unhelpful direction. Without a separate requirement, a product could be optimised for the number on the front of the pack while offering comparatively little at the long wavelength end. The circled mark exists to close that gap by tying ultraviolet A protection to the labelled factor, so that a manufacturer cannot raise one without raising the other.
This is worth stating because it explains why the mark is expressed as a proportion rather than as an absolute figure. A fixed absolute threshold would be trivially met by high factor products and unreachable by low factor ones. A proportion scales with the claim being made, which is a more elegant piece of regulatory design than it is usually given credit for, and it is also the reason the mark cannot be read as a level.
Why the two marks are not comparable
A pack can carry the circle and no stars, stars and no circle, both, or neither, and each combination means something specific.
The circle without stars indicates the recommended relative minimum is met, with no information about how comfortably. Stars without the circle indicate a stated balance between the two bands, with no assurance about the relative threshold. Both together are the most informative combination available on a British pack, and it is still less information than a technical buyer would have from the underlying test reports.
Neither mark tells a reader the absolute ultraviolet A protection factor as a number, because that number is not conventionally printed. This is a genuine gap in what a label communicates, and it is one of the clearer examples of the distance between what the industry measures and what the shelf shows.
Critical wavelength, the third quantity
Sitting behind the circle is a second criterion that almost never appears on a pack: critical wavelength. It is the wavelength below which ninety per cent of a product's ultraviolet absorbance sits, and a higher value means the absorbance extends further into the longer wavelengths.
The recommendation behind the circle sets a minimum of 370 nanometres. The same value appears in the United States as the basis of the definition of broad spectrum, which is why the phrase has a precise meaning in one jurisdiction and a looser one elsewhere. That is covered in broad spectrum and what it requires.
What happens when a mark is absent
Absence is not evidence of poor performance, and it is regularly read as though it were. A product without the circled mark has not necessarily failed the recommended relationship. It may not have been tested against it, it may have been formulated for a market where the mark is not used, or the artwork may simply predate the convention. The mark records a claim a manufacturer has chosen to make and can support, and a manufacturer is not obliged to make it.
The same applies with more force to the star rating, which is a voluntary proprietary system. A pack with no stars carries no implication whatever about the balance of its protection. Reading absence as failure produces the odd result that a reader penalises a product for a claim it did not make, which is the reverse of how claim regulation is meant to work.
What a reader can reasonably conclude from an absent mark is only that the pack is telling them less. That is a real disadvantage when comparing products, and it is a disadvantage in information rather than in protection.
Reading the two marks together
The usable reading is sequential. Take the factor as the scale of protection against the reddening effect. Take the circle as confirmation that ultraviolet A protection has been held to a proportion of that scale. Take the stars, if present, as a description of the balance, remembering that the balance is relative to the same product and not to any other.
What you cannot do is add them together, trade one against the other, or treat a high star count on a low factor as equivalent to a lower star count on a high factor. Those are different products with different absolute protection.
What to take from this
The circle is a pass mark whose bar moves with the factor. The stars are a ratio expressed in bands. Neither is a level of ultraviolet A protection stated in absolute terms, and no British pack conventionally gives you that figure.