Sun Protection: How to Choose and Use Sunscreen
Broad spectrum, SPF 30–50, a shot glass of it, reapplied every two hours — plus mineral vs. chemical, and the spots everyone misses.
Choose a broad-spectrum sunscreen rated SPF 30–50 for days outdoors. Broad spectrum filters both UVA (deep-penetrating, causes aging and dark spots) and UVB (burns the surface); both raise skin-cancer risk. Apply about 1 fl oz (30 ml) 15 minutes before going out and reapply every 2 hours, or immediately after swimming or heavy sweating. Mineral formulas suit sensitive skin; chemical formulas rub in clear but can harm coral.
Sun protection is a year-round piece of outdoor gear. Hiking, skiing, paddling — the exposure adds up whether you feel it or not.
Forms of Sunscreen
- Lotion or cream: the most common type; needs to be rubbed in evenly.
- Stick: packable, not subject to liquid limits, easy to carry for touch-ups.
- Spray: fast and convenient, but spray carefully and get even coverage.
Broad Spectrum Only
Broad-spectrum sunscreen filters both UVA and UVB. UVA drives photoaging and dark spots and penetrates deep; UVB burns the surface. Both increase skin-cancer risk — so "broad spectrum" is not a marketing extra.
Mineral vs. Chemical
- Mineral (physical): zinc oxide or titanium dioxide forms a reflective barrier on the skin's surface. Gentle and well tolerated — a good fit for sensitive skin — but tends to leave a white cast.
- Chemical: absorbs UV and converts it to heat. Transparent with no white cast, but harmful to coral reefs. Oxybenzone has been banned in some regions specifically for reef protection.
Picking an SPF
| SPF | UVB blocked | Right for |
|---|---|---|
| SPF 15 | 93% | Mostly indoor, everyday life |
| SPF 30 | 97% | Occasional time outside |
| SPF 50 | 98% | Long days outdoors |
| SPF 100 | 99% | High-risk skin |
Applying It Right
- Use about one shot glass — 1 fl oz (30 ml) — per application, and put it on 15 minutes before you go out.
- Reapply every 2 hours, and immediately after swimming or heavy sweating.
- The spots people miss: the nose tip, the ears, the backs of the hands, the back of the neck.
Easy to Forget
- UV gets stronger with altitude, and snow and water both reflect it back at you.
- Overcast skies and window glass still let burns through.
- For babies under 6 months: use shade and clothing, not sunscreen.
This is general guidance, not medical advice. See a dermatologist for suspicious moles, persistent sunburn or skin damage.