Protecting your skin from the sun comes down to a combination of sunscreen, clothing, shade, and timing. No single strategy blocks all ultraviolet radiation on its own, but layering several approaches together dramatically reduces your risk of sunburn, premature aging, and skin cancer. Here’s how to do it well.
Why UV Rays Damage Skin
Sunlight contains two types of ultraviolet radiation that reach your skin: UVA and UVB. They cause different kinds of damage. UVB rays have shorter wavelengths and higher energy, penetrating the outer layer of skin where they trigger sunburns and direct DNA damage. UVA rays penetrate much deeper, passing through the outer skin, into the underlying dermis, and even into subcutaneous tissue. That deep penetration is what breaks down collagen and elastin over time, leading to wrinkles, sagging, and dark spots.
Both types contribute to skin cancer risk. And while UVB is strongest during midday hours, UVA intensity stays relatively constant throughout the day and passes through clouds and glass. That’s why sun protection isn’t just a beach day concern.
Choosing the Right Sunscreen
Look for a sunscreen labeled “broad spectrum,” which means it filters both UVA and UVB rays. SPF only measures UVB protection. An SPF 30 sunscreen blocks about 97% of UVB rays, letting roughly 3% through. SPF 50 blocks about 98%, letting 2% through. The jump from 30 to 50 sounds large but only filters one additional percentage point of UVB, so SPF 30 is a solid minimum for daily use.
If you want to gauge UVA protection specifically, look for the PA rating system common on Asian and European sunscreens. PA stands for Protection Grade of UVA, and it uses a plus-sign scale: PA+ offers some UVA protection, PA++ offers moderate, PA+++ offers high, and PA++++ is the highest level available. More plus signs mean more UVA defense.
Mineral vs. Chemical Formulas
Mineral sunscreens use zinc oxide or titanium dioxide. These sit on the skin’s surface and physically reflect UV rays away, like a shield. They start working immediately and tend to be gentler on sensitive or acne-prone skin, though they can leave a white cast.
Chemical sunscreens use ingredients like avobenzone, oxybenzone, and octinoxate. These absorb into the skin, soak up UV rays like a sponge, and convert them into heat that dissipates. They tend to blend in more easily and feel lighter, but they need about 15 to 20 minutes after application to become effective. Either type works well when applied correctly.
How Much to Apply and When to Reapply
Most people use far too little sunscreen. To get the SPF level printed on the bottle, you need about two milligrams of sunscreen per square centimeter of skin. In practical terms, that means a nickel-sized dollop for your face alone and a full shot glass (about two tablespoons) for all exposed areas of your face and body. If you’re using a spray sunscreen, apply until you see an even sheen on the skin, then rub it in.
Reapply every two hours when you’re outdoors. That window shrinks significantly with water and sweat. Swimming can weaken and wash off sunscreen within 45 minutes to an hour, even with water-resistant formulas. Sweating from exercise or yard work has the same diluting effect. Sport or sweat-resistant sunscreens buy a few extra minutes, but don’t expect them to last a full two hours in those conditions. After toweling off, reapply right away.
Spots People Forget
Sunburn loves the areas you skip. The ears are one of the most commonly missed spots, and skin cancer can develop on any part of the ear, including the inner bowl that seems protected. The tops of your feet get heavy exposure in sandals or flip-flops. Your scalp gets UV exposure through thin hair and along your part line. A hat helps, but if your hair is fine or thinning, apply sunscreen directly to the scalp or use a UV-protective spray designed for the hairline. The back of the neck, the backs of hands, and the chest just below the collar are other frequent blind spots.
Sun Protective Clothing
Clothing is one of the most reliable forms of sun protection because it doesn’t wear off or need reapplication. Fabrics are rated using UPF, or Ultraviolet Protection Factor, which measures how much UVA and UVB radiation can pass through. A UPF 50 shirt blocks 98% of UV rays, allowing only 1/50th to reach your skin. UPF 30 to 49 is considered very good protection, and UPF 50 or higher is rated excellent.
Not all clothing offers strong protection. A typical white cotton t-shirt has a UPF of about 5 to 7, and that drops further when the fabric is wet. If you spend a lot of time outdoors, dedicated UPF clothing is worth the investment, especially long-sleeved shirts, wide-brimmed hats, and neck gaiters. Dark, tightly woven fabrics block more UV than light, loosely woven ones.
Shade, Timing, and Sunglasses
UV radiation peaks between roughly 10 a.m. and 4 p.m. Planning outdoor activities outside that window cuts your exposure substantially. When you are outside during peak hours, seeking shade under trees, umbrellas, or canopies helps, though UV rays can still bounce off water, sand, concrete, and snow to reach you from below and the sides. Shade works best as one layer in a broader strategy.
Sunglasses protect the delicate skin around your eyes and the eyes themselves. Look for lenses labeled as blocking 99% to 100% of UVA and UVB rays. Wraparound styles offer the best coverage because they block light entering from the sides.
UV Exposure Through Windows
Standard glass filters out most UVB rays, so you’re unlikely to sunburn sitting by a window. UVA is a different story. Clear glass can transmit up to 72% of UV radiation depending on its thickness. Tinted glass reduces that to around 40%, and double-glazed residential windows with clear panes still allow roughly 57% of UVA through. That matters if you sit near windows for long stretches at home, in an office, or while driving. If you notice sun damage mainly on the left side of your face (for drivers in the US), window-transmitted UVA is likely the reason. Window film rated for UV blocking or applying sunscreen on your face as part of your morning routine addresses this.
Sun Protection for Darker Skin Tones
Melanin, the pigment that gives skin its color, does provide some natural UV defense, but it tops out at roughly SPF 13. That’s far below what dermatologists recommend for meaningful protection. While skin cancer rates are highest among non-Hispanic white populations, people with darker skin tones are more likely to be diagnosed at an advanced stage, which leads to worse outcomes. Squamous cell carcinoma is the most common skin cancer in people with dark skin, and it often appears in areas not typically associated with sun exposure, like the lower legs and feet.
Sunscreen matters for every skin tone. If white cast is a barrier, tinted mineral sunscreens or chemical formulas that absorb without residue are practical alternatives. The goal is the same: broad spectrum, SPF 30 or higher, reapplied every two hours outdoors.