Summer might be inching toward its final stretch, but the sun is still shining bright — and your skin still needs protection. Whether you’re soaking in the last beach weekends or just running errands, UV rays are still at work and can cause damage year-round. Let’s talk sunscreen — not just slathering it on but really knowing how it works and why it matters.
What Is SPF, Really?
You’ve probably seen “SPF 30” stamped on sunscreen bottles, but what does it mean? SPF (Sun Protection Factor) measures how much UVB light — the kind that causes sunburn and damages skin cells — the sunscreen blocks. An SPF 15 lets about 7 percent of UVB through, SPF 30 about 3 percent, and SPF 50 just 2 percent. Higher numbers mean more protection, but none offer total defense, so aim for SPF 30 or higher.
Why UVA Matters, Too — and What ‘Broad Spectrum’ Means
SPF tells you about UVB, but UVA rays are the sneakier kind. They don’t burn but they age skin (think wrinkles and spots) and raise skin cancer risk. That’s why “broad spectrum” on the label matters. It means protection from both UVA and UVB.
How Sunscreen Actually Protects You
Sunscreen works in two main ways:
- Mineral filters (such as zinc oxide) sit on your skin’s surface, reflecting rays like tiny mirrors.
- Chemical filters (such as avobenzone) absorb UV light and turn it into harmless heat.
Many formulas use both, giving balanced coverage.
Applying It the Right Way
Where people typically fall short is using too little or skipping reapplication. Aim for about an ounce (roughly two tablespoons) for full-body coverage and reapply every two hours or more often if you’re swimming or sweating.
Regular sunscreen use can reduce your risk of melanoma by around 50 percent and other skin cancers by roughly 30 percent. Skin cancer is the most common type of cancer in the United States and worldwide—one in five Americans will develop it by age 70, says Dr. David Wong, a board-certified dermatologist in the Hill Physicians network.
“If you have a family history of skin cancer, you’re at higher risk,” Dr. Wong explains. “Be diligent about minimizing UV exposure. Avoid tanning beds, wear a wide-brimmed hat and protective clothing and use a broad-spectrum sunscreen with SPF 30 or higher.”
Don’t Stop at Sunscreen
Even the highest-level sunscreen works best when it’s part of a bigger sun-safety plan. Stay in the shade during peak hours, wear sunglasses and choose clothing with built-in UV protection. And yes, cloudy days and indoor time by sunny windows still count for UV exposure.
Already caught our Sun Science Safety post? Consider this your follow-up guide for making sunscreen a habit, not a hassle.
Final Thoughts
The sun might be setting soon on summer 2025, but the need for skin protection never fades, especially in California. Your skin works hard to protect you, so return the favor. Stay consistent with sunscreen, schedule regular skin checks and don’t hesitate to ask your doctor for advice on staying safe from the sun all year long.
