/ Health

Do you know your UVA from your UVB?


It’s a good time to stock up on sunscreen, but working out which bottle offers the best protection isn’t easy. This guest post from Nina Goad explains all, from SPF to star ratings.

It’s getting to that time of year, a stuttering start maybe, but the first sunny days of the year are definitely here. As things begin to heat up, and spring turns to summer, more of us will be dropping a bottle of sunscreen into the shopping basket.

The question is though, what sort of sunscreen do you want to go for, and what do the labels mean? Surveys have shown that most of us only have a vague idea of what the numbers on sunscreen bottles actually mean, and what level of protection we should be aiming for.

The sun’s rays from UVA to UVC

When talking about sun protection, it is useful to understand a little about what we are protecting ourselves against – UV radiation. UV radiation from the sun is transmitted in three wavelengths – UVA, UVB and UVC. UVC does not penetrate the earth’s atmosphere, so we only really need to protect against UVA and UVB.

UVA is associated with skin ageing. UVA leads to wrinkles and sun-induced skin ageing, as well as skin cancer. UVA can pass through window glass and penetrates the skin more deeply than UVB.

UVB is the form of UV irradiation most responsible for sunburn and has strong links to melanoma and basal cell carcinoma risk, two types of skin cancer.

If you find it hard to remember which is which, some experts recommend remembering it as ’UVAgeing‘ and ’UVBurning’.

What does SPF mean?

SPF, or Sun Protection Factor, is the level of protection that the sunscreen offers against UVB rays, so it can be understood as the sunburn protection factor.

The British Association of Dermatologists recommends a minimum of SPF of 30. Used in conjunction with other sun protection methods, such as finding shade and wearing protective clothing, including a hat, this will give you a good level of protection from the sun.

What about UVA?

In addition to the SPF number, you may well have noticed that most bottles have a UVA logo, the letters ‘UVA’ printed in a circle, or a number of stars.

The UVA logo indicates that the sunscreen meets the EU recommended level of UVA protection. If your sunscreen uses the star rating system for UVA labelling, we would recommend a minimum of four or five stars.

It’s very important to realise that under both these systems the ratings are always in relation to the SPF – so if your SPF is low, your UVA rating will be low too.

I hope this has helped clear up some of the more confusing aspects of sunscreen labelling, so that you’ll know what to look out for next time you’re shopping. However, I think you’ll agree that the system is unnecessarily complex.

This is a guest post by Nina Goad, Head of Communications for the British Association of Dermatologists. All opinions are Nina’s own, not necessarily those of Which?


I am very disappointed by your lack of noting the escalating allergy issues to MI/MCI preservative contained in sunscreens. The reason Ultrasun is really expensive is that is the only sunscreen that is declared MI/MCI free.

For latest report showing rates of sensitisation in uk have now increased to 6% ie over 3.5 million sufferers in UK alone – it is probably a lot more as it is very difficult to get diagnosed.

Hi Mark. There are many sunscreens that do not contain MI/MCI preservatives. Ultrasun is just one of them.

I’d like to see it flagged in the Which? test. I did google searches & it was the only one I found.
I am just a normal person & I don’t have detailed information about which products are safe.
I think there should be a UK register of safe UK products. A lot of the website are mixed up with US respondents.

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It is difficult to put sun cream on when you are allergic to it. It is not an advert, it took me a whole weekend to find a sun cream for my daughter. I am on the same side, I am trying to prevent cancer. The product I ended up getting only got 3 stars in the test & now I am very worried.

Andrew Birnie says:
27 May 2016

I can confirm that Altruist Dermatologist Sunscreen is MI free. It was developed to be suitable for people who often intolerant of sunscreen and have a low risk if allergy. It’s only £4 for 200ml and now £14 for a litre on Amazon. Still very high quality, but not designed with profits in mind, rather the reduction of skin cancer.

I’ve never heard of Altruist sunscreen, but I wish I found out earlier as I spent a fortune on Ultrasun after spending ages trying to find a MCI/MI free sunscreen.

Joe says:
24 June 2016

Hi Nina. I’ve been told about altruist by a doctor and have purchased a bottle.. I’m concerned though because it doesn’t have the uva ibn ked or uva area. Does this mean it hasn’t been tested and had the seal of approval? Obviously only want to use the best for my kids.

Joe says:
24 June 2016

Sorry..that was supposed to read uva or uvb circled. Or the uv stars.

Nina – can I thank you very much for the article but more importantly explaining why it was limited in its extent. Your prompt answering of the queries raised is also excellent.

And thanks to Mark for highlighting an issue I was unaware of.

Forgive me for being dim but having read the report that Mark mentions I realised that my knowledge is small so :
1. Once sensitised is one like that for life?
2. If one is sensitised does this make one more prone to other irritants?

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Sorry to hear that DL,. It must make life that much more intense ; but not in a nice way.

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Reading these articles lead me to think a stronger reaction must be made against companies whose products are damaging people. I am surprised That biggest legal action in US was only $1million dated 11Nov15. Could this be something which could campaign on ?

Thank you for a delightfully clear article, Nina, which confirms my belief that the only safe way to visit the tropics is either by staying indoors or wearing a Yashmak when sunbathing. There’s a double problem with sunscreens and that’s the interaction with mosquito repellents.

But the evidence is (and has been) pointing towards both UVA I and II as being not only up to 50 times more prevalent but potentially just as dangerous to the fair skinned (and others) as UVA B. Partly this is because of its greater ubiquity (it’s hitting you even when the day is cloudy) but also because the longer wave length allows it to penetrate certain substances more easily. And both A I and II and B suppress the immune system, which doesn’t help when they do so much damage to the body’s systems as it is. So in short, stay in between 11 and 4 during what we ironically call the ‘summer months’ if you’re fair (and take care even if you’re not) and get your vitamin D out of a bottle.

Nina – Thank you for the links which made for some very disturbing reading. The woman who suffered so badly from paint was really quite horrific.

i have to admit to being slightly astonished ” Prior to 2005, MI had to be mixed with MCI and was generally found in concentrations of around four parts per million (ppm) in personal care products. However, from 2005 MI was permitted for use on its own in far higher concentrations – up to 100 ppm – which is a 25-fold increase on the previous levels of the preservative and widely thought to be responsible for the disease increase.”

I thought the EU was a centre for precautionary measures and here we have something with a 25 fold increase and apparently no adequate testing. Is there a backstory we should know?

I see that , as if by coincidence, ” Experts say incidents of allergies are occurring faster than they did to methyl­dibromo glutaronitrile, another preservative that was banned from use in cosmetics in 2005 after it was linked to an increase in eczema cases. ”

So it looks like the EU Commission without much thought agreed to ban one eczema causing chemical and to up the limit for another at the behest of the industry they regulate.

If I can ask was this flagged up by Which? as I do not recall it being mentioned. With a hit rate of around 10% of the population and its use in sunscreens …..

I must admit that I also knew nothing about MCI/MI, fortunately my daughter had private medical insurance through work, however it still took us a year to get to the bottom of the problem. She really suffered during that time. Once you know the products, acrylic nails, hand wash, nail varnish, shampoo, shower gel etc & the symptoms of MCI/MI allergy, it seems so obvious. However trying to ascertain if a product contains it when there are so many trade names is a nightmare. I will get reading Nina’ s links, I am really delighted that she came back to us so quickly. This is a worldwide problem, not just the EU. I must admit we don’t understand why it has not been banned. I know it is a much bigger problem than thought due the difficulty of diagnosis.
I have just told my daughter about our conversation, she is really pleased, as we still have a lot of questions.

MCI or MI is in a lot of products eg face wash, shampoo, conditioner, shower gel, hair styling products, face wipes, deodorants, face care, baby wipes, after-shave products, moisturisers, make up, soaps,
Which? has never mentioned it in any article.
The EU have not banned them.
I do not understand the reasons.

Christina Hespe says:
9 March 2020

Little late to the party, but this may be useful to anyone now reading this thread: http://mi-free.com/mi-free-sunscreen-and-sun-cream/

Steve says:
28 May 2016

Hi Nina Our sunscreen says it also protects against ‘long ‘ UVA which I’ve not seen before. Is long UVA a big issue ?

Given that people tend to go abroad for sunny holidays i was curious as to what was the situation in the US – particularly given the possible problems of taking fluids etc through airports. The bottom line is that Which? should advise on the shortfall of US products for the benefit of the annual 4 million British visitors to the US.

Apparently the EU regulations, despite problems , is seen to be better than the US control. e.g. this was one study in 2009

” Also, the Food and Drug Administration requires sunscreens to be topical, which means that your skin won’t absorb them into the bloodstream. But last year, a CDC study found the common UVA blocker oxybenzone in the urine of 2,500 people who regularly used sunscreens. Another CDC study found that babies born to mothers whose urine contained significant amounts of one type of oxybenzone weighed noticeably more or less at birth than those in a control group. The highest concentrations of the chemical occurred in white women, who use more sunscreen.”

So moving forward to 2016 what is the situation there in the USA :

“Many products offer poor protection. This year, the group looked at more than 750 products and concluded that nearly 75 percent of them offered poor protection or had ingredients the group found “worrisome.” For example, oxybenzone is a sunscreen additive that the working group says is a hormone disrupter and allergen.

Sonya Lunder, a senior analyst for the Environmental Working Group, says it’s a good thing that the number of mineral-only products has doubled since 2007, rising from 17 percent of products to 34 percent in 2016. These sunscreens, which offer protection against both UVA and UVB, generally don’t contain harmful additives.”

It is worth looking at the site for all their tips

Of particular relevance is this:
” British researcher Brian Diffey evaluated the UV protection of four U.S. sunscreens and four sold in Europe, each of which had an SPF value of 50 or 50+. He found that the U.S. sunscreens allowed, on average, three times more UVA rays to pass through to skin than European products, which included the modern UVA filters (Diffey 2015). ”

However the FDA are not totally toothless:
“It’s already clear that some European chemicals should not be admitted to the U.S. market. For instance, Merck has applied to FDA for permission to market a sunscreen ingredient called 4-MBC or Enzacamene, a UVB filter. Researchers have detected 4-MBC in European women’s breast milk and in wildlife (Krause 2012). These findings are troubling because laboratory tests suggest that 4-MBC disrupts the hormone system (Krause 2012). Hormone disruptors pose particular dangers to the fetus because small perturbations to hormone systems could cause lasting changes in the developing brain, thyroid and reproductive system. “

Apologies if I have missed it – but an important piece in the jigsaw seems to have been missed from the discussion. Companies make sunscreens to make money – not to prevent illness. And one of the ways that is an effective selling tool is to frighten the pants of people by only giving one half of the story.

So what is the other half of the story? Well, there is overwhelming evidence that many illnesses are related to latitude, for example, cancers and Type 1 diabetes since the synthesis of vitamin D, essential to health, decreases the further you go from the equator in either direction.

I will quote from the book “Doctoring Data” by Dr Malcolm Kendrick –

“Here are just two stand-out facts from a major study in the Annals of Epidemiology entitled ‘Vitamin D for Cancer Prevention’

Women with higher solar UVB exposure had only half the incidence of breast cancer as those with lower solar exposure.
Men with higher residential solar exposure had only half the incidence rate of fatal prostate cancer.

To put that in simple English, if you spend longer in the sun, you may be far less likely to die of breast and prostate cancer (and lots of other cancers as well, ….

But what about the increase risk of dying of skin cancer! I hear you cry. Well, what of it? Around 2000 people a year die of malignant melanoma in the UK each year ……

On the other hand, breast cancer kills around 20,000 a year, as does prostate cancer”

So these 2 cancers (breast and prostate) alone, I stress alone, kill 20 times the number of people as melanoma and that is not even considering the numerous other diseases linked to low vit D levels.

I am not suggesting that everyone should go out into the midday sun in Britain in the summer months without some protection – but the idea that it is safest to slap on layers of sun cream at all times of day and thus prevent the sun from providing vitamin D could, on balance, be far more damaging to health – even if it provides lots of profit for the manufacturers.

Diana Smith says:
31 May 2016

I am surprised you have not mentioned Altruist sunscreen. Developed by my consultant dermatologist
Dr. Andrew Birnie. Please look at it. Only £4.00 for 200mls via Amazon.

Andrew Birnie gave information on this product earlier in this Conversation but without declaring an interest.

I will get some Altruist next time, shame Which? did not test it.
Now I just need him to develop a list of Uk Sold products without MCI/MI in them.
Are there any surprising beauty products/make up that may contain MCI/MI that my daughter should watch out for?
I’ll have to read the rest of these conversations now….

In ‘Which’ edition June 2016 (page 60) my wife and I struggled to make sense of the caution about sun exposure time, viz “The number relates to time…. However, the time starts as soon as you step into the sun and doesn’t get reset each time you reapply the sunscreen – it’s set for the day.” I wonder how many people understand that? We certainly didn’t and assumed that re-applying cream extended the period of protection i.e. regularly re-applying even a low SPF cream throughout the day would reset the clock and protect you all day.

It’s hard to understand the principle behind this. Could you explain it more simply for us?

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Let’s assume a very sensitive skin that would burn in strong sunshine in 10 minutes. Applying the correct application of SPF 15 screen would give a maximum of 15x10minutes=2½ hours protection against burning. So 2½ hours after the first application we could re-apply that same sunscreen but get no further protection that day i.e. despite the new application of sunscreen we’ve already reached its limit of burn protection (for the particular individual) and subsequent sun exposure puts us at risk of burning, even after using sunscreen.

That’s what we didn’t understand thinking that the fresh application of cream would again protect us from burning for a similar period of time.

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It seems really important for us to be aware that lower SPF sunscreens would, after a few hours, leave anyone with sensitive skin at risk of burning, even if they had fastidiously and constantly re-applied sunscreen.

I see now that the total daily exposure time is a one-off maximum i.e. SPF factor x individual’s unprotected skin-burn time. High factor screens applied regularly are the safest bet it appears, just as we’re constantly told. That and wearing suitable sun-protection clothing and hats!

The UVAPF (protection factor) should be derived in accordance with an international standard that the UK publish as BS EN ISO 24443:12. It measures the UVA absorption of a defined thin film of protection cream on a roughened acrylic substrate. Calculations then derive the protection factor. My guess when sun cream is used in practice is that controlling the film thickness will be the main difficulty (other than abrasion or rinsing). Slapping it on will be prudent but costly. So renewing the film regularly will be the best way. Personally, I’d stay out of the sun as much as possible if it is strong, wear a hat and a long-sleeved top. I don’t really see the attraction of a tan other than to impress your neighbours when you come back from holiday. I wonder why suntanning has otherwise become a been a popular pastime?

My primary concern is avoiding burning and minimising the risk of cancer and actinic keratoses. I’m nearly 70 and have eventually realised how much damage uv rays do to skin and every cryo treatment on my head further reminds me!

In strong sunshine abroad I wear a black, wool cowboy-style hat, in the UK a Tilley. An SPF 30 hiking shirt with a black SPF15 polo shirt underneath keeps the sun off my shoulders and back when hiking.

Tanning is of no interest to me but I accept that it is for others.

At one time, sunbeds were considered safe and UV light was used for various skin conditions. We are still learning. I’m not convinced that it is possible to apply sunscreen evenly.

Obviously the risk of cancer is the main problem but who wants to to look like a wrinkled prune when they get older? I do my gardening in the evening if is a sunny day and I don’t sit in the sun, never mind sunbathe.

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You say that you do not think “once-a-day”, “eight-hour” claims should be made on sunscreen products in the UK, but you should check out Ultrasun’s claims on QVC. what worries me is that this claim is made alongside a picture of a mum with a young child.
“Ultrasun offer a range of high level sun protection products that work to shield you against UVA and UVB rays and are suitable for children and those with sensitive skin. One application is all that’s needed for all-day defence against harmful sun damage.”
I have bought the Ultrasun SPF50 for my husband who burns very easily, and he lathers it over his bald head but then slaps a cap over it. He also uses the plunge pool when on holiday.Now you suggest that that there may a considerable decrease in the SPF protection. I was thinking of getting some for my pregnant daughter who is about to go on holiday and very lax about sun screen. I shall save my money and advice her to go for Nivea and make her partner nag her accordingly.