UVA protection factor

The short answer

UVA protection factor — often written UVA-PF or UVAPF — is a way of measuring how much a finished sunscreen reduces UVA-induced pigment darkening compared with unprotected skin.

It complements SPF. SPF mainly tells you about UVB protection and sunburn; UVA-PF helps describe the UVA part of the protection picture.

Why SPF is not the whole story

UVA and UVB are both ultraviolet radiation, but they are not identical. UVB is strongly linked to sunburn, which is why SPF testing leans heavily on it. UVA reaches longer wavelengths and matters for pigment darkening and photoageing.

That is why a sunscreen with a big SPF number still needs a meaningful UVA claim. In Europe, the Commission recommends a UVA protection factor of at least one third of the labelled SPF for products making the relevant claim^[3].

How UVA-PF is measured

The in-vivo ISO 24442 method is designed to determine a sunscreen's UVA protection factor^[1]. One established biological endpoint is persistent pigment darkening, usually shortened to PPD. A 2000 study found this endpoint could reliably measure how much UVA reached protected versus unprotected skin^[2].

You do not need to memorise the lab method. The useful idea is that UVA-PF belongs to the finished formula. You cannot calculate it by adding up the exciting filters listed on the back of a tube.

Why labels look different

Depending on where you shop, UVA protection may appear as:

• a UVA-PF or PPD number
• a PA grade
• a UVA circle
• a broad-spectrum claim
• no consumer-facing number at all

The label language varies, but the practical choice stays familiar: use a tested sunscreen with broad coverage, apply enough, and reapply when exposure is long or the film is rubbed away.

Mads's practical read

UVA-PF is useful label language because it stops SPF from doing all the talking. If pigmentation is a concern, read the whole protection claim and wear the product generously.

For the everyday application part, see how much sunscreen to use on your face. The best label detail in the world cannot help if the sunscreen stays in the bag.