Overview

• Health authorities recommend at least SPF 30 for everyday use and SPF 50+ in intense UV environments like water or snow
• Apply sunscreen at 2 mg per cm² of skin—about four heaped tablespoons for an adult—15 to 30 minutes before going outdoors to form an optimal protective film
• Sweating, swimming or toweling off reduces sunscreen efficacy even for water-resistant formulas, so reapplication every two to three hours is essential
• Mineral UV filters such as titanium dioxide and zinc oxide are preferred for their reflective protection and lower risks to human health and marine ecosystems
• Stored unopened in a cool, dry place, sunscreen remains effective for up to 30 months but should be used within 12 months once opened to avoid rancidity