The sun is shining and we have to protect ourselves from it’s harmful rays. If you’re headed outdoors keep some sunscreen with you, and if you pull a half-empty, sand-caked tube of last summer’s sunscreen out of your beach bag, check the expiration date before using it. Most sunscreens are designed with specially formulated stabilizers that protect its potency for up to three years, but that’s assuming you didn’t let it bake for days in your backyard. “Leaving sunblock in intense heat for a prolonged amount of time may make it less effective,” says Mitchell Chasin, M.D., medical director of Reflections Center for Skin and Body in New Jersey and fellow of the American Society for Laser Medicine and Surgery. So store sunblock in a cool place, and while you’re at the beach, keep it in the shade.