SPF and PA, explained
Korean sunscreens show a PA rating as well as SPF. Here’s what the labels mean, and why sunscreen is the most proven anti-ageing step of all.
Strong evidence
What it is
SPF measures protection from UVB, the rays that cause sunburn. PA is a rating used in Korea and Japan for protection from UVA, the rays that go deeper and cause most of the lines, sagging and dark spots linked to the sun. PA+ is the lowest and PA++++ the highest.
UK and EU sunscreens show UVA protection differently, with a UVA logo in a circle (meaning UVA protection is at least a third of the SPF) or, at Boots, a star rating.
What the research shows
In a four-and-a-half-year trial of 903 adults, people who used sunscreen every day showed no detectable increase in skin ageing, while those who used it when they chose to did. Daily users had 24% less skin ageing.
Hughes and colleagues, Annals of Internal Medicine, 2013 [1]
UVA makes up most of the UV that reaches us, passes through clouds and glass, and is a major cause of photoageing, which is why both SPF and UVA protection matter.
European Commission Recommendation on sunscreen labelling, 2006 [2]
No cream, serum or device has better evidence for keeping skin younger-looking than wearing sunscreen every day.
Who it suits
Everyone, every day, all year. After 40, sun damage shows as dark spots, crepiness and loss of firmness, and daily protection helps slow all of these. It also stops retinoids, acids and vitamin C from making your skin more sun-sensitive.
How to use it after 40
- Choose SPF30 or higher with high UVA protection (PA+++ or PA++++, or the UK UVA logo).
- Use about two finger-lengths for face and neck, as the last step of your morning routine.
- Reapply if you’re outdoors for long. A sun stick is handy for topping up over make-up.
- Korean sunscreens are popular because they’re light and leave no white cast, so you’re more likely to wear them daily.
Sources
- Hughes MCB et al. Sunscreen and prevention of skin aging: a randomized trial. Ann Intern Med. 2013.
- European Commission. Recommendation 2006/647/EC on the efficacy of sunscreen products and the claims made relating thereto. 2006.
This page is general information, not medical advice. Last updated 4 November 2026.
Our sunscreens
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