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 In 2016 Which? put several once-a-day sunscreens to the test, investigating how long they lasted on volunteers in a controlled lab experiment, and found they didn't offer nearly as much protection as claimed.

According to the Met Office, even when the weather is overcast, UV radiation can still be 80% of its normal levels. Not to mention, the temperature can be deceiving – especially if there’s a breeze making it feel a lot cooler than it is. So even if it's cloudy it's important to protect yourself. We agree that the claim “Once a day” can be anticipated in a wrong way by the consumer, and it is one of the reasons why we changed our durability communication from “Once a day” to “Up to 10 hours”.A spokesperson told us that all of its sun creams are designed for 'longevity' but that it found the use of the word 'durable' more 'appropriate' than once a day. This tends to mean that two commonly used chemical UV filters linked to coral bleaching – oxybenzone and octinoxate – aren’t used. 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? 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.

People can still use these types of sunscreens, but you should treat them like any other sunscreen, and reapply regularly,' he said. Consider the time of day – If you're spending time in the sun without wearing sun cream, you should only do so before 11am or after 3pm, as the middle of the day is when you're at the greatest risk of getting burnt. It's clear that there are plenty of conditions to fulfil to get the claimed protection from once-a-day products, which may be hard to achieve if you're on a day out in the sun. 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.'Even with our test subjects just sitting on a chair in a T-shirt, we saw substantial reductions in the level of sun protection, so we don't think you can rely on once-a-day sun cream to keep you protected all day. 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. 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.

They were allowed to wear t-shirts and sit on a chair (we did this because if you lie on a sun lounger or towel, get sandy, or wear a t-shirt on holiday it’s possible your single-use sunscreen could be rubbed off over time). For 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 sunFrom April to September, when the UV Index is generally higher. It takes 10 to 15 minutes of sun exposure each day for those with fair-to-olive skin to get enough vitamin D. Physical/mineral products reflect visible light as well as UV, which can make the formulations opaque and leave a white residue on the skin. Some formulations use nanoparticles of titanium dioxide and zinc oxide – the minerals responsible for the residue. Nanoparticles are smaller, and as they scatter visible light – rather than reflect it – the sun creams are transparent. How to use sun cream The British Association of Dermatologists (BAD) says frequent reapplication of sun cream is important, regardless of how long any product claims to give protection for. Sun cream provides protection from sunlight using UV filters. These are classified into two types: chemical and physical – also known as mineral sun cream. What's more, even if you follow all the rules, it's possible you won't get as much as protection as you expect.