10 Questions About Sunscreen Answered by a Proper Scientist with Nothing to Sell

Because there's a lot of fake news about sunscreen out there... Stay protected, people

Welcome to Sunscreen Season. Every day I receive countless emails, mostly from PRs just doing their job and telling me about their clients’ new/old sunscreens. And most of them start with a version of this: “We all know we need to wear sunscreen 365 days of the year…”

So let me stop them right there.

You do not need to wear sunscreen every single day of the year.

Well, maybe you do:

If you have experienced melanoma, have someone in your family who has had skin cancer, or have a lot of moles, then you might need to wear it 365 days of the year.

If you experience melasma, or patchy pigmentation, or you’re finding your melasma suddenly got worse because of hormonal changes eg contracpetion or pregnancy, then maybe your sunscreen and a good tyrosenase inhibitor might help prevent it.

If you are recovering from a transplant operation, or have an autoimmune condition, you are at an elevated risk of skin cancer and should be vigilant about sun protection all year - check with your doctor.

If you are undergoing laser treatment, use retinol, and have been advised by your dermatologist to wear it every single day of the year, then just pop it on.

That’s already quite a few people. A lot of us, even.

But everyone else?

You do not. Unless the UV is three or above.

In this month’s British Vogue, I interviewed sunscreen brand founders, and their scientists, and what I found really interesting was just how many of the experts I interviewed don’t wear sunscreen every day. (The article went online today and you can read it here) They wear it in the summer months, or when they’re on holiday. They believed they needed the vitamin D the sun gave them naturally, they also didn’t want to absorb too many unnecessary chemicals. Despite selling their own brands, they didn’t feel the need to tell everyone to wear it every single day, and I respected them all the more for this honesty.

There was one expert - a sunscreen brand training manager from a reputable brand - who said “yes” you need to wear it every day “to create good habits” by which I think she meant, if you just get into the habit of wearing it in the winter months on a daily basis, you’ll just do it without thinking on those warmer days when the sun can cause more damage. But when I pressed her for guidance on what exactly those “good habits” entailed, she couldn’t answer. She had no scientific evidence to back up her claim. It frustrated me so I didn’t include her answers in the piece.

I wanted to talk to someone who had no vested interest in selling us sunscreen, couldn’t care either way whether we bought it or not, and so I asked the leading dermatologist Christopher Griffiths, who he might recommend, and this led me to hit Sunscreen Gold! Enter, the esteemed Brian Diffey, mostly retired now, but the Emeritus Professor of Photobiology in the Dermatology department at Newcastle University. A scientist - not a dermatologist - he specialises in sun exposure and the effects of sun on the skin. He has worked in hospitals and alongside dermatologists. He invented the Star Rating adopted by Boots - the same Star Rating they still use today. He also invented the system used in the US for broad spectrum protection, used on both normal skin and diseased skin. There isn’t a thing about sunscreen this man does not know. And most importantly, he has no skin in the game - if you’ll excuse the pun - because he has never made his own sunscreen brand. (The sunscreen industry is globally valued at approximately $14.9 billion. By “industry” I’m talking about traditional, mineral sunscreens as well as those other “state of the art” ones with the latest nano-tech. I mean, with the greatest respect, if you’d invested a ton in creating your own sunscreen brand, you would want everyone to wear it as much as possible, surely? Which of course makes those experts I interviewed in the Vogue piece who were so honest about not wearing it every day, all the more credible).

Anyway…Brian. I thought it would be useful to include here a little more from Brian, because I find it alarming and frankly really annoying that there is so much misinformation about sunscreen, a lot of which is framed around protecting ourselves from skin cancer. At a time when people have enough to deal with, do we really need to be scaremongering? Do we need teenagers to be buying one more totally unnecessary product, or mums to be slathering it all over their kids when honestly, a place in the shade with UV protective hats and clothing probably costs less in pounds per wear and is going to be far less hit and miss? If I have learnt one thing, it’s to question every piece of information about sunscreen that comes my way, because as Brian says (admittedly in relation to my question about infra-red) when false information is repeated over and over by experts… “Suddenly it becomes conventional wisdom”. And I appreciate I play a part in that.

Please remember, these are Brian’s views based on years and years of research, he has written hundreds of peer-reviewed papers many of which you can find online, as well as a recent book “Sun Protection: a risk management approach” - but - if your dermatologist is telling you something else, listen to them, they’re looking at your skin after all. I’m not anti-sunscreen at all, but I am pro-using it wisely and prioritising other methods of sun safety first, as you’ll see from Brian’s advice below…

Here are 10 Questions I asked him about sunscreen:

1. With years of experience researching our skin and sunscreen, what is your own personal approach to wearing sunscreen? Do you wear it even on a grey-sky sort of day?

“On a grey day I will wear a moisturiser without an SPF as I don’t want to compromise my vitamin D production, but in the Summer, to be honest, I don’t use sunscreen much at all. What’s right and wrong about it? Well, it can be messy and sticky, and often it’s not that pleasant to apply. What I tend to rely on much more is a hat with a brim, which I wear for much of the year mainly because I don’t have a lot of hair on top. It provides good protection over the face, nose and ears. You’re more at risk of sunburn the higher the sun is in the sky around the middle of the day. And when the sun is high, you get excellent protection from a hat with a brim - and this is what I rely on. The only time I wear sunscreen is if I’ve got a short sleeved shirt on while cycling or walking, and if I know I’m going to be out in strong summer sunshine for an hour or two. Clothing and shade are much more effective at protecting our skin than sunscreen, which is often applied haphazardly.

2. If you were to make your own sunscreen, what would you want to be its key benefits?

“Firstly, it needs to be pleasant to use so that I’m more likely to apply it generously, as the thicker it’s applied, the more it absorbs the sun’s ultraviolet (UV) rays.

Using a product with a high SPF, such as SPF50, will help compensate for under-application, but high SPF products incorporate higher concentrations of the active ingredients, which can increase the possibility of undesirable effects both in ourselves and in the environment.

Manufacturers have realised that compliance is as important as a sunscreen having the right technical properties such as SPF and UVA Star Rating - people need to want to use it, and not have it sitting in a drawer.

3. How should we apply sunscreen? How much?

“People generally apply sunscreen thinly and haphazardly, so they miss bits and they don’t end up with the protection they think they’re getting from the labelled SPF. Sunscreen has a useful role to play but it’s not the be all and end all. Sunscreen is tested in a laboratory to an internationally agreed thickness of 2mg per square centimetre. But this doesn’t reflect human behaviour and typically people will apply it at around 1mg per square centimetre. So, if you apply an SPF of 50 sunscreen in the way that most people do, you’ll end up with an SPF of 25 or thereabouts. Very few people who use a sunscreen will get the protection they think they’re getting.

4. Some of the arguments I've heard lately in favour of wearing sunscreen every day include: "it helps form good habits". Is there any truth in this?

“My personal view is this is totally the wrong advice. It’s not a good habit. It’s a bad habit. You shouldn’t do it. Use the sunscreen when your exposure to the sun is going to be potentially detrimental. On a typical winter’s day in the UK, you might travel to work, pop out to lunch, and in doing so you’ll get the equivalent of around 45 seconds of summer sunbathing. On a rainy day it’s the equivalent of 15 seconds. This amount of sun exposure is biologically trivial. If you do apply sunscreen to your skin [in those environmental situations], first it’s unnecessary, but secondly, there are side effects associated with sunscreen use: you can get contact and photo contact reactions, as well as systemic absorption which means the active ingredients are absorbed in the bloodstream. They’re probably not doing a lot of harm, but who knows? With some nanoparticles there is some concern there may be a risk for humans. As well as potential risks in humans of unnecessary sunscreen application, it can also be harmful to the environment - sunscreen washed off our skin or discharged during manufacturing goes down the drain and out into the oceans. Some of the active filters have been shown to damage coral reefs and marine life. Sunscreens aren’t without their side effects. You should definitely use them when the need arises, but there is no need over winter in the UK.

5. What about if I use a moisturiser with a sunscreen? Is this a good thing to do?

“Sunscreens in moisturisers may be helpful in the summer months. When you put a sunscreen into a moisturiser, it generally has properties that don’t bind well to the skin. A good sunscreen should bind well to the outer layer of the skin. Most don’t bind well to the skin if they’re just added to moisturisers. If you put on an SPF 15 in the morning, by lunch time it will be down to an SPF 5, because you touch your face etc, so you’re ending up with a low SPF by lunch time. There’s a risk also you’ll compromise your vitamin D - the sun produces 90% of our vitamin D needs. So you don’t need to use sunscreen from about mid-October to about mid-March in the UK if you are an indoor worker, spending most of your day indoors.

6. Do we need sunscreen for infra-red and blue light protection as well as UV?

“Whilst some manufacturers now market products claiming to protect against infrared and/or blue light, the level of protection provided is actually very small. Furthermore, I am not persuaded that there is any benefit in protecting from these parts of the sun’s spectrum.

“Sunscreen contains ingredients that attenuate the ultraviolet rays of the sun. It’s these rays that cause the acute effect of sunburn - your skin goes red - and over many years, chronic exposure especially during the summer months increases ageing and your risk of cancer. All of this is caused by ultraviolet rays.

“When you’re outdoors in the summer about half the UV rays reaching your skin come from direct sunlight, the other half come from sunlight that has been scattered in the atmosphere and reaches its way down to the earth from all parts of the sky. Scattering of sunlight in the atmosphere is why the sky looks blue and not red. Virtually all of the infra-red we are exposed to comes from direct sunlight. If you stand under a tree so that the sun isn’t reaching your skin but you can see all the sky around you, there will be virtually no infra-red reaching you.

“A sunscreen labelled SPF of 30 would only have an infra-red protection factor of about 2. So the reason for putting infra-red on the bottle, is that [the manufacturers] are hoping it will give their product an edge. If one manufacturer does it, then the competitors do it, and suddenly it becomes conventional wisdom.

“Blue light is much the same, although in some people it can exacerbate melasma. Obviously the best way to protect yourself is to keep your clothes on. The blue light coming from laptops and screens is absolutely miniscule – in fact, it’s so small you need highly specialised equipment to measure it so you certainly do not need to protect your skin against any very low levels of blue light coming from screens. Blue light exposure, especially before bed, suppresses the natural production of melatonin, a hormone that regulates sleep so best not to play with your phone or iPad before bedtime.

7. What do you think is good about sunscreen today?

“New UV filters have been developed that have better properties at absorbing UV rays. Manufacturers have improved the sensory properties of sunscreen, and they’re much more pleasurable to apply now than 20 years ago. They’re using a combination of filters - maybe five or six to provide balanced protection across the UV spectrum. They’ve got better both in terms of their technical performance and their cosmetic acceptability.

8. We talk a lot about “healthy skin barriers”. If your skin is healthy will that give you extra, or even natural, protection to the sun?

“No not at all. When UV enters the skin it causes DNA damage in our cells but mostly these get repaired. Occasionally the damage doesn’t get repaired properly and this becomes a mutation which over time can multiply and become a skin cancer. Having a healthy skin barrier, with a healthy microbiome makes no difference to protection from the sun.

9. What’s your biggest bugbear about sunscreen?

“I don’t really have one, but I suppose claims that are unnecessary. Saying a product can protect against infra-red is conning people into thinking they need something they don’t.

Look at the article about Sunscreen claims - false beliefs and misguided advocacy.

Journalists often think they need to speak to dermatologists about sun safety. But the problem is that the dermatologists’ expertise is in diagnosing and treating skin disease, and not necessarily in the physics of the atmosphere or sunscreen chemistry. As a consequence, some professionals fall into the trap of telling journalists what they think they know rather than what they know they know, with the result that false information and misguided beliefs are passed on.

10. You mention not wearing sunscreen from October through to March - in the UK at least. How do I know when I need to wear it?

“In Australia where skin cancer as a result of sun exposure is a real problem there was a revised statement from the Australia and New Zealand Journal of Public Health, Balancing the Risks of Sun Exposure, 2023. The new advice is that you only need sunscreen when the UV index was forecast to reach three or greater. In England, typically the UV index is below three every day from October through to early March. I was saying this 20 odd years ago.

“The sun is good for you! Insufficient sun exposure has become a real public health problem - published in the International Journal of Public Health - to quote:

“Studies in the past decade indicate that insufficient sun exposure may be responsible for 340,000 deaths in the United States and 480,000 deaths in Europe per year, and an increased incidence of breast cancer, colorectal cancer, hypertension, cardiovascular disease, metabolic syndrome, multiple sclerosis, Alzheimer’s disease, autism, asthma, type 1 diabetes and myopia. Vitamin D has long been considered the principal mediator of beneficial effects of sun exposure. However, oral vitamin D supplementation has not been convincingly shown to prevent the above conditions..”

“Don’t be paranoid about avoiding it. From October to March in the UK climate, get any sunshine that is around.

NB: For those living in Australia or in hotter climates than ours in the UK, Brian suggests letting the Nambour study be your guide. This was conducted in Queensland where the sun’s UV levels are sufficiently high that sun protection is advisable all year round. This was flagged by Substacker Ken Corbett, whose comment you can see in the Comments section below, thank you Ken!