The use of the word durable, she added, aims to communicate its long lasting characteristics without 'promising [a] full day protection guarantee, with no need for reapplication.'

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. People can still use these types of sunscreens, but you should treat them like any other sunscreen, and reapply regularly,' he said. 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.What's more, even if you follow all the rules, it's possible you won't get as much as protection as you expect. We award Which? Best Buy status to products that we've independently reviewed that meet all our tough criteria: they must pass independent lab tests for UVA and UVB sun protection, and be easy and pleasant to apply.

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. 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. 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.Nobody applies sunscreen perfectly uniformly to all exposed skin and it is inevitable that we will miss patches of skin. 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? It takes longer for those with darker skin that rarely burns – it can take 25-40 minutes for the darkest skin type. 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 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.