People can still use these types of sunscreens, but you should treat them like any other sunscreen, and reapply regularly,' he said.

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 sun It's common for sun creams to claim to be 'water resistant', but this doesn't mean that they're waterproof. Reapply sunscreen after swimming, sweating heavily, towel drying, or rubbing your skin in a way that might cause the cream to rub off. 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). It takes longer for those with darker skin that rarely burns – it can take 25-40 minutes for the darkest skin type.

Professor Brian Diffey adds that sun creams generally offer ‘very good’ water resistance these days (though be aware water resistance claims also come with caveats, and the products we tested didn't hold up well to real-life conditions in our 2016 investigation), which is good if you're planning on spending time in the pool or in the sea. But over the course of the day swimming will wash away some of the protection. When choosing sun cream for your child, look for a short ingredients list and the terms 'fragrance free' and 'hypoallergenic'. The WHO recommends 35ml of sun cream (seven teaspoons' worth) to cover an adult, so use around a quarter to a half of this depending on the size of your child. 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.' We asked Boots a series of questions about its Once sun cream range and asked it to respond to our concerns about 'once a day' claims. Casting incorrect assertions in this manner is misleading and confusing to customers and we are disappointed that Which? has chosen to do this.' Calypso

Apply evenly and generously, smooth in gently. We recommend a minimum quantity of 35ml for all over body protection. Remember, sun cream is just one part of staying safe in the sun and it's also really important to encourage kids (and adults) to: Eat well, live better and stay healthy - sign up for our free monthly Food & Health newsletter for the latest insights delivered straight to your inboxThe British Association of Dermatologists (BAD) says frequent reapplication of sun cream is important, regardless of how long any product claims to give protection for. What's more, even if you follow all the rules, it's possible you won't get as much as protection as you expect.

Over the course of a day, he added, 'swimming, drying, sweating, getting dressed and undressed' can cause sun cream to be wiped or washed away.Sun cream provides protection from sunlight using UV filters. These are classified into two types: chemical and physical – also known as mineral sun cream. Some people worry that using sun cream might prevent them from getting enough vitamin D, but this isn’t the case unless you really overdo it. 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.' Boots 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? Mineral sunscreens in particular often promote their environmental credentials, the most common being that they’re ‘reef-safe’ or 'ocean-friendly'.

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.Don't just rely on sunscreen either: use clothing, hats, sunglasses to cover up, and seek shade, particularly when the sun is strongest, between 11am and 3pm - regardless of whether you are wearing sun cream.