Most people apply far less than they need. For your face and neck, aim for about a half-teaspoon. For your whole body, about a shot glass full (roughly one ounce). Don’t forget commonly missed spots like your ears, the back of your neck, your hairline, and the tops of your feet.

Yes. Clouds only block a portion of UV rays, and UVA rays, the ones linked to aging and skin cancer, can pass through cloud cover and even car windows. In Alaska, snow reflects UV rays back up at your skin, which is why sunscreen matters just as much on the slopes in February as it does at the lake in July.

Not by much. SPF 30 blocks about 97% of UVB rays, and SPF 50 blocks about 98%. The bigger factor in how well you’re protected is applying enough sunscreen and reapplying it, ideally every two hours, or right after swimming or heavy sweating.

It can, though it’s not common. Certain chemical filters, fragrances, and preservatives are the most frequent culprits. If you have sensitive or reactive skin, a fragrance-free, mineral-only sunscreen is a good place to start. If a rash or irritation keeps happening, we can help you pinpoint what’s causing it.

Mineral sunscreens (zinc oxide and/or titanium dioxide) are generally the best-tolerated option for children, since they tend to be gentler and less likely to irritate young skin. For babies under 6 months, keeping them in the shade and covered up is preferred, with sunscreen used only when shade and clothing aren’t enough.