SPF: UVA and UVB, what to look out for and how often to apply

I’m one of the very few people in the UK who, whether the sun’s out or it’s pouring with rain, wears SPF every day. I don’t know what it is about sunscreen that bothers people so much, but there’s this misconception we only need sunscreen when we’re away on holiday – and I’ve never understood why. Particularly when, as soon as the temperature goes 5 degrees above normal, we all slip into shorts and T-shirts and end up a sorry shade of salmon (isn’t that a Steps song?).

Clearly it’s something that irks me, not least of all because of the health risks that come from going without protection. It also means that, when it comes to choosing a suitable SPF, most people really know what they’re looking for, and go for either a) the product that offers the best value for money or b) the most expensive and assume it’s the best. So, in this skincare series I’m going to talk through the basics of SPF and break down what’s actually important , and the key signs and symbols you should be looking for while browsing the supermarket shelves.


First of all, you want an SPF that gives you UVA and UVB protection – which, on US products, will often be labelled ‘broad spectrum’. “What does that mean? And how do I know I’ve got the right protection?” I hear you say. Well…

UVA: ‘A’ is for ageing. This is what causes lasting damage

Around 90% of the visible signs of ageing come from sun damage – and, more specifically, UVA rays. These are long waves that penetrate deep into the skin’s epidermis, causing lasting damage that won’t be apparent initially, but will start to show up over time (i.e. fine lines and wrinkles, pigmentation, etc.).

If your sunscreen has the UVA seal on the package – that’s the letter’s “UVA” written in a circle – it meets EU requirements, offering a minimum 1/3 of the SPF protection. Within the seal, UK brands also include a star rating of up to 5 stars, which compares the efficiency of the UVA protection with the UVB protection.

UVB: ‘B’ is for burning. This is what causes immediate damage

UVB rays will be most intense between 10am and 2pm, and this is proportional, depending on your location, the time of year, etc. These are short waves that affect the top layers of the skin, so any type of burning – whether it’s a slight tingle or a full blown blister – will be caused by UVB. Hence, they’re what most people are looking to block with their SPF.

Protection from UVB rays is the number on the front of the bottle, which tells you how much longer you can spend out in the sun without getting burnt than you could without protection. So, if you can usually sit out for 10 minutes, SPF 30 means you can stay in the sun for 300 minutes without getting burnt (10 x 30).

Back to the UVA protection – any sunscreen with the UVA seal will allow you to stay out for one third of this time as a minimum. So, if SPF 30 gives you 300 minutes (5 hours) of UVB protection, it’ll give you 100 minutes (1 hour 40 minutes) UVA protection (10 x 10). This is really what’s important – but if you want to go a step further, a higher star rating obviously indicates better UVA protection.

Make sense?

How much and how often?

We often equate burning with skin cancer, and for good reason – research has shown that if a child gets 5 sunburns throughout their childhood, they’re 80% more likely to get skin cancer. But both UVA and UVB rays have been linked to the disease, so it’s equally important to make sure you’re protected against both.

With a lot of beauty and grooming products, applying excess is just a sheer waste of money, but the risks that come as a result of not using SPF make it more of a health product than a cosmetic treatment. Therefore, more is more, and if you’re out in the sun consistently (on a beach, for example), it’s recommended that you re-apply every two hours – regardless of the claims on the bottle. Using sunscreen doesn’t stop you from getting a tan – it just stops you from burning. That’s true for all factors, from 5 to 50, so I’d always use a high factor, ideally 30 or 50.

When it comes to applications, here are the basics:

  • A full body application of sunscreen should be at least six teaspoons, which is equivalent to around 35ml
  • Re-apply after going in water, drying yourself, putting clothes on and taking them off, etc.
  • Apply classic sunscreens around 30 minutes before going out in the sun; mineral formulas can be used immediately before going out
  • On the face, apply after moisturiser but before make-up – and always use a dedicated SPF as well as the protection that comes in products
  • Throw your sunscreen away after one year – the chemicals start to break down and it’s not effective anymore (Tip: write the date you opened it on the lid, so you don’t forget)

I hope you found that helpful. In the second part of this SPF series I’ll be sharing my favourite sunscreen products, as well as some new releases that go that little bit further. So remember to like and subscribe to keep up to date with all the latest posts, all I’ll see you next time.


1 Comment

  1. Kate Murray
    10th July 2019 / 5:49 pm

    SPF in the rain!! Wow, I had no idea!! Super informative, thanks for sharing!

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