Cover up – wear sunglasses to protect your eyes and grab a hat if you need to keep your face out of the sun. You might also want to wear a T-shirt, which can help to cover up typically over-exposed areas such as shoulders.

Bear in mind that running at altitude means you’ll be more exposed to UV rays – up to 10% more for every 300 metres above sea level,’ he adds. ‘Nobody ever regretted wearing sunscreen, but we have all regretted skipping it… Skin damage is long-lasting, difficult (if not impossible) to reverse and yet massively avoidable.’ How often should you apply facial sunscreen? You can buy sun cream in pharmacies, supermarkets and discount stores, with some of our tested options coming from Asda, Boots, Garnier, Nivea and Wilko.People can still use these types of sunscreens, but you should treat them like any other sunscreen, and reapply regularly,' he said. So, if you are only applying your sunscreen once a day, you are at risk of spending hours in the sun with little or no protection to those areas of skin that may have been missed.' The sun emits two types of ultraviolet radiation. UVA affects the skin’s elastin, leading to wrinkles and premature ageing (although it’s also linked to developing skin cancers). UVB is responsible for sunburn and can increase the risk of skin cancers, too. Certain sunscreens carry a UVA star rating from zero to five, which indicates how much UVA radiation they absorb, relative to UVB radiation. Don’t be alarmed if there isn’t a number on the bottle, though: the rating system was devised and is owned by Boots, so not all brands carry it. There’s a long list of ingredients that are used as chemical absorbers, so it’s easiest to simply look for products that are labelled ‘sensitive’ rather than search for specific ingredients. SPF make-up: does it really offer protection from the sun?

Yes, you can - but you’ll also need to reapply frequently, just like you would if you were on the beach staying dry, and immediately after towel drying. Believe it or not, the best thing you can do for your skin daily is to apply a sunscreen. Not only will this reduce the chances of your skin ageing prematurely, but it will also protect you against harmful skin cancers. And if you think sunscreen is only essential on sunny days, think again. For maximum protection, you’re supposed to apply it even when it’s cloudy outside – and even if you spend most of your time indoors. My advice would be to find a sunscreen that you enjoy wearing, that doesn’t interfere with your joy of running, and build it into your ritual the same way you do with fuelling and stretching,' says Austen.It takes longer for those with darker skin that rarely burns – it can take 25-40 minutes for the darkest skin type.

Since our 2016 investigation, the CTPA has advised brands to voluntarily stop making 'once a day' claims and move towards using the word 'durable' instead. If you don’t know your SPFs from your UVAs and UVBs, read on as we shed some light on what to look out for with our handy buying guide below – before listing our favourite sunscreens on the market right now. Mineral sunscreens in particular often promote their environmental credentials, the most common being that they’re ‘reef-safe’ or 'ocean-friendly'. Casting incorrect assertions in this manner is misleading and confusing to customers and we are disappointed that Which? has chosen to do this.' Calypso A spokesperson added: 'As with all sunscreens, it is important to follow the instructions for application and use; and sunscreen should not be used to intentionally stay longer in the sun. Sunscreen is just one part of a sun safe regime.' BootsFor more details on the importance of vitamin D and where to buy supplements, see our in-depth vitamin D guide . Other ways to stay safe in the sun

Sweat-resistance: ‘You also want something highly water and sweat-resistant, meaning it won’t slide off or drip into your eyes during your workout,’ says Austen. The British Association of Dermatologists suggests that an SPF of 30 and a star rating of four out of five is “generally considered as a good standard of sun protection” (as long as this is paired with protective clothing and periods spent in the shade). The EU recommendation is that creams should offer UVA protection that’s at least a third of the SPF, so if you see a bottle with the letters UVA in a circle, you can be assured that it meets this minimum requirement. Sunscreens that offer strong protection against both UVB and UVA radiation are termed “broad spectrum” products. Physical or mineral sun creams create a barrier on the skin that acts like a mirror, reflecting and scattering the UV light.Babies less than six months old should be kept out of direct sunlight, according to the NHS, and the skin of young children should be protected from the sun when UV levels are high. However, there's no agreed definition of 'reef-safe', research is still ongoing as to the impact of these chemicals, and our tests found many mineral suncreams failed to protect as claimed – so take any claims with a pinch of salt. Kids' sun cream This tends to mean that two commonly used chemical UV filters linked to coral bleaching – oxybenzone and octinoxate – aren’t used.