Sunscreen is important – got it. But what’s the difference between UVA and UVB? And what about SPF vs PA? Should I be wearing mineral or chemical sunscreen? Where to start? Right here. This simple, straight-talking guide will take you through the ins and outs of sun protection to cover everything you need to know about sunscreen.

Why you should care

We all know that sunscreen protects against sunburn, but this product has become so much more than a summer holiday essential. The winter sun may not burn skin – or even be visible through the clouds – but it can cause damage to skin nonetheless. Over time repeat unprotected exposure to sunlight can cause hyperpigmentation which results in uneven skin tone. It will also prematurely age your skin with wrinkles and dark spots, and of course heighten the risk of skin cancer. Regularly wearing SPF will help protect against all of these attacks on skin.

What is the difference between UVA and UVB rays?

Well that’s not quite the full picture: there are actually not two but three types of UV rays, as sunlight travels to earth in a combination of visible and invisible rays:

  • UVA travels through the atmosphere almost uninterrupted
  • UVB rays are only partly blocked by the atmosphere
  • UVC radiation is the most dangerous form of UV light, but luckily it does not reach the earth’s surface because it is blocked by the ozone layer in the atmosphere

How do UVA and UVB rays affect the skin?

Neal’s Yard Remedies Formulation Chemist Cindy Lauret explains: ‘Sun exposure can harm your skin in two major ways: UVA (A for Ageing) penetrates deep into the dermis, the skin’s thickest layer and is responsible for prematurely ageing skin and DNA damage which causes skin cancer. UVB (B for Burning) affects the top layer of skin and tans the skin, but too much exposure can lead to sunburn and consequently, skin cancer’.

SPF vs PA, what is the difference?

Cindy shares the key differences: if you’re based in Europe you’ll most likely be familiar with the SPF (Sun Protection Factor) rating for sunscreen, but if you live in Asia you’ll also see the PA rating. What does that mean? Simply put, they are two different systems used to measure sunscreen protection against UV rays. In addition to that, you’ll find the term ‘broad spectrum’ on packaging to highlight a sunscreen that protected against both UVA and UVB rays. And in the UK, just because we like to do things differently, we also have the Boots star rating which was developed in 1992 by the high street chemist to indicate the strength of protection.

What number should I look for?

You probably already know this, or can guess for the rating systems you’re unfamiliar with: the numbers you see after ‘SPF’, as well as the ‘+’ signs after PA and the stars wit the Boots rating are all there to help you determine how long a sunscreen will protect the skin when exposed to UV rays. So the higher the number, the higher the protection. You’ll struggle to find much higher than SPF50, which is considered very high protection. Same goes for the PA and Boots star rating: PA++++ is the highest rating and Boots have a maximum of 5 stars on their sunscreens. SPF relates to protection from UVB rays whilst the PA rating, star rating and UVA logo indicate the level of protection from UVA. Skin tone does play a part in how much natural protection we have, but Cindy is quick to point out it’s not as much as you may think: ‘your tan is only as protective as SPF2+ sunscreen. A person with very fair skin should wear at least SPF30 anytime they head outdoors, whether they’re spending 15 minutes or two hours exposed to the sun’s rays. In contrast, a person with very dark skin is less likely to burn, and may require only SPF15 to protect their skin for up to four hours’.

As an example, for my fair to light skin (a mix of English, French and Italian heritage) I would apply UpCircle SPF25 Mineral Sunscreen or Nourish Skin Protecting Daily Moisturiser SPF25 when I know I’ll have only gentle sun exposure: a light spring or autumn sun, or a day spent mostly indoors. Both of these are great all year round options as they double up as your moisturiser and provide reliable protection. If I’m spending most of the day outside then I’ll ramp up to SPF30 – Soleo Organics Everyday Extra-Lite Natural Sunscreen SPF30 is my most recent discovery – and reapply regularly. And for the summer and beach holidays it’s got to be SPF50, always. My new favourite is Dr Orga Taicho Cica End Sunscreen SPF50 PA++++.

How much should I apply?

If you follow Instagram skinfluencers you will have seen the two-finger method where you squeeze the sunscreen along the length of your pointer and middle finger. That’s how much you should apply on your face and neck. But for the rest of your body a common unit of measure will be the teaspoon:

  • Face and neck = Half teaspoon
  • Legs = 2 teaspoons
  • Arms = one teaspoon
  • Back and torso = one teaspoon

If in doubt, reapply – unlike makeup, you can never be wearing too much sunscreen.


What is the difference between mineral (also known as physical) and chemical sunscreen? They are different types of UV filters. A mineral sunscreen contains naturally occurring active ingredients like titanium dioxide and zinc oxide to form a protective barrier on your skin’s surface to physically prevent UV rays from penetrating the skin. This is why you will often experience a white cast which can give you a ghost-like aura, although my two most recent mineral sunscreen discoveries from UpCircle and Nourish luckily don’t have that issue. Chemical sunscreens protect the skin differently: the UV light is absorbed into the skin, but the sunscreen then converts the light into heat. There is ongoing debate around the safety of chemical sunscreens, some studies suggesting that these chemicals are absorbed into the bloodstream. It is however pretty universally accepted that the benefits of regularly applying sunscreen – and therefore protecting yourself from skin cancer – far outweigh the potential risk of absorbing sunscreen chemicals. So whichever format works best for you, slather it on!

What does reef safe mean?

There is ongoing debate around the safety of certain chemicals found in sunscreens and their harmful effect on coral and other marine life. Hence the flurry of products branded as ‘ocean friendly’, ‘environmentally friendly’, ‘biodegradable formula’ and ‘reef safe’. The jury’s still out, although in 2021 Hawaii banned over-the-counter sales of sunscreens containing oxybenzone and octinoxate, thought to exacerbate the reef bleaching. If you prefer to err on the side of caution, mineral sunscreens containing zinc oxide and titanium dioxide offer the protection needed without harming marine life. Both UpCircle and Nourish’s SPF25 sunscreens are good options, with UpCircle using non-nano zinc oxide and Nourish offering a COSMOS certified organic formula.

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