This was a simple, clear, and useful podcast episode from Shortwave on the 6 biggest sunscreen mistakes.
Here are the ones I found most useful:
- Dermatologists replace their sunscreen every spring. The active ingredients in an already open bottle can degrade, and bacteria can get in too.
- SPF isn’t as important as I thought. SPF 15 blocks out 93% of UV rays, and SPF 30 blocks out 97%. Going for SPF 50 or 80 has rapidly diminishing marginal benefits.
- Rather than worry about SPF, focus on putting on enough sunscreen. You need a shot glass worth for your body (25mls), and about a teaspoon worth for your face.
- Dermatologists often see the worst burns from overcast days. Don’t forget to protect on cloudy days too.
- Regularly reapply sunscreen. If sweating or swimming, reapply every 80-90 minutes.