Wearing sunscreen is one of the best — and easiest — ways to protect your skin’s appearance and health at any age. Used regularly, sunscreen helps prevent sunburn, skin cancer and premature aging. To help make sunscreen a part of your daily routine, dermatologist Anna Chien addresses common concerns. What is SPF? Sun protection factor (SPF) represents a sunscreen’s ability to protect against a specific portion of ultraviolet (UV) light called UVB. UVB rays are responsible for sunburns and skin cancer. There are two other portions of UV light: UVC rays (which don’t pass the earth’s atmosphere) and UVA rays (which are also responsible for skin cancer as well as skin aging). A sunscreen that is broad spectrum will protect against both UVB and UVA rays. What sunscreen should I buy? For day-to-day use, pick a sunscreen with an SPF of at least 30. If you spend time outdoors, choose a product with SPF 60 or greater. In reality, most people do not use as much sunscreen as they should, and this higher SPF helps compensate for the reduced application. How much sunscreen do I need? To protect your face, neck, arms and legs, you’ll need about 1 ounce of sunscreen. Squeezed into your hand, 1 ounce of sunscreen is enough to completely cover your palm. To protect your face and neck, you’ll need about a half teaspoon. Should sunscreen come before or after other products? So long as the sunscreen is at least SPF 30, water-resistant and broad-spectrum, it doesn’t matter in what order you apply your skin care products. Some people find it’s easiest to work with bare skin — before makeup or moisturizer have been added. Find what works best for your routine. If you have concerns about layering specific products, speak with your dermatologist. Does makeup with SPF work? Makeup is not enough to protect your skin — even if it has a high SPF. You would need much more makeup than you typically use to reach the labeled SPF. Are mineral sunscreens better? Sunscreens are often grouped into two categories: chemical and mineral. Chemical sunscreens use ingredients like avobenzone, octisalate, octocrylene, homosalate and others. Mineral sunscreens use either zinc oxide or titanium dioxide. Both chemical and mineral sunscreens work similarly (by absorbing UV light and transforming that energy into negligible amounts of heat). Mineral sunscreens also reflect a small amount of UV light. For some, chemical sunscreens can sting. If you have sensitive skin or frequently react to products, mineral sunscreen might be a better choice. The downside of mineral sunscreens is that they often leave a noticeable white cast, particularly on skin of color. Otherwise, it’s a personal choice. The best sunscreen is the one you’ll reach for every day.