Once you’ve brushed up on the best sunscreen to buy for the fam, there are the all-important rules of usage. We drilled Dr. Nanette Silverberg, a Manhattan-based pediatric dermatologist, on how to navigate a sun-safe day at the beach.

If you’re headed out for a day at the pool/beach, should you lather up your kids before leaving home, or wait until you arrive at your destination? Great question! There are 2 types of sun protection agents, chemical and mineral (sometimes called chemical-free)—the latter being best for young kids. Chemical sunscreens need a half hour to interact with the skin for maximal protection, whereas mineral blocks work instantly. A head-start is best either way, because it’s easiest to apply sunscreen to clean, dry skin. Don’t forget swim shirts and shorts with UPF, hats and sunglasses. Any tips for application? The curves of the face require the most time, so I start there. Creams and gels require one coat (use a dollop and massage it gently into the skin), sprays require two. Use a stick for the face and spray for the body. How frequently should sunscreen be reapplied on children? Every 1-2 hours on exposed skin, and sooner if they swim with sunscreen that is not water-resistant. Pick a sunscreen that is SPF 30+, 45+ is even better, broad spectrum for UVA-protection, and water-resistant, with 80 minutes being the maximum on a label. That gives you an hour and twenty minutes at full potency in the water, and can be used as a rule of thumb for re-application. Is it OK to use sunscreen that’s not “kid-specific” on children? I use baby mineral blocks for the whole family because they are usually lower in fragrance and I like the fact that I can see where the sunscreen is when I put it on, aiding in even application. From a safety perspective, the AAP recommends chemical-free for babies from 6-24 months. If your child gets wet in the pool, ocean, etc., is it important to re-apply sunscreen immediately after they get out? Sunscreens should be reapplied every 1-2 hours, especially after sweating or swimming. Using a sunscreen that is broad spectrum with a higher SPF and water resistant to 80 minutes helps maintain potency in warm swim weather. And finally, what should parents be watching for in terms of burning and overheating? The youngest children who can’t express themselves are at greatest risk. Even short midday activities in the outdoors can result in sunburn and dehydration. Planning to avoid the sun at its peak—10AM to 3 PM—helps. Consult a pediatrician about the safety of outdoor excursion if your child has health issues. Thanks, Nanette!