If you religiously apply sunscreen at the height of summer but are somewhat less diligent in the winter months, you’re not alone. A study published in The Archives of Dermatology found that many people are less likely to use sun protection because they presume that cold temperatures and clouds block harmful UV radiation.¹ But did you know that there’s a type of UV radiation that’s actually equally strong all year long? Not only that, but the UV rays that cause skin cancer are still a very present danger to your skin in the winter months.

Let’s take a look at the compelling reasons why you should remember to wear your SPF even in cold and cloudy weather.The sun exposes our skin to two types of ultraviolet (UV) radiation — ultraviolet A (UVA) and ultraviolet B (UVB). While both are dangerous to your skin, UVA and UVB have slightly different effects. UVA has a longer wavelength and is associated with accelerated skin aging while UVB has a shorter wavelength and is associated with sunburn and skin cancer.

Both types of UV radiation cause DNA damage and together are responsible for an estimated 90% of visible skin aging.² This damage is largely cumulative, which means that even small doses of radiation can have a big impact on your skin over time. That’s why dermatologists recommend wearing sunscreen every day, even if you aren’t going to be spending enough time in the sun to get a sunburn. You probably know that sunscreen protects your skin from UV radiation. But do you know how it works? The answer largely depends on the ingredients inside your favorite sunscreen.

Sometimes called physical or natural sunscreens, inorganic sun protectants like zinc oxide and titanium dioxide act like a physical shield on the surface of the skin. By reflecting UV radiation away from the skin, these ingredients protect you from the DNA-damaging impacts of UV rays.

Organic sun protectants, on the other hand, actually convert UV radiation into heat before it can damage the skin. Often called chemical sunscreens, these include ingredients like avobenzone and oxybenzone.

Both types of sun protectants are considered safe and can effectively block both UVA and UVB radiation. However, some ingredients work better to block UVA than others, so be sure to look for a broad-spectrum sunscreen that specifically block both types of rays.If you want to protect your skin from the aging impacts of UV rays, it’s equally important to apply sunscreen on the darkest winter days as it is on the brightest summer mornings. That’s because UVA radiation–the type that causes dark spots and wrinkles–remains constant throughout the year, no matter the season. Harmful rays from the sun are still present and the UV levels are just as strong as any other season. These rays easily penetrate both clouds and glass, so you can still get exposure on a cloudy day or if you’re sitting indoors near a window.

UVB radiation, on the other hand, does vary in intensity throughout the year. But because UVB rays cause the majority of skin cancer, it’s important to take any possible exposure seriously. While these rays are less strong during the winter months and even weaker if you live on a very northern or very southern latitude, they can still cause sunburns and sun damage year-round in most regions, especially if there’s snow on the ground.³

Snow can reflect up to 80% of UV rays. That means that you’re actually getting a double dose of exposure: once when the rays hit your skin directly and again when they reflect off of the snow onto your skin.⁴ In comparison, sea foam reflects about 25% of UV, and dry beach sand reflects about 15%.⁵ That means that in the winter season, you might actually be safer from UV rays on the beach than you are on the ski slopes.

In fact, if you’re spending your winter on the slopes, you might also have the high altitude to thank for increased UV exposure. At higher altitudes, the layer of atmosphere between you and the sun is thinner. This means that UV rays have less distance to travel and are stronger when they reach your skin than they are when you’re at sea level.⁶ This reinforces that wearing sunscreen in winter is still necessary to prevent effects of sun damage regardless of the season.Wearing sunscreen indoors is something that we don’t always think about, but it’s still important for protecting our skin and overall health. UVA rays can still pass through windows and cause some skin damage. Sunscreen acts as a protective barrier from air pollutants that are often found inside our homes and offices. In today’s world, we often use our digital devices at home and work which contain blue light. Blue light can still penetrate the skin and cause damage just as much as the sun's UV rays can.The American Academy of Dermatology recommends using a broad-spectrum sunscreen with a sun protection factor (SPF) of at least 30 every day of the year. And because winter conditions like blustery winds and damp snow can wear away your sunscreen and lessen its efficacy, it’s best to reapply every two hours. Finally, don’t rely on sunscreen alone. Wear sunglasses to protect your eyes from UV radiation, and a hat to shade your face. To learn more about sunscreen and sun safety, visit the American Academy of Dermatology’s FAQs.

• There are two main forms of UV radiation that affect your skin: UVA and UVB radiation.
• UVA radiation is tied to skin aging and remains constant throughout the year, even in winter months.
• UVB radiation is tied to sunburn and skin cancer. Although it varies in intensity throughout the year, it is still a real danger to your skin in winter months.
• Snow and high altitudes can magnify the effects of UV radiation, making your skin more vulnerable during common winter activities like skiing and snowboarding.
• Incorporate SPF into your skin care routine all year round to keep your skin safe from the aging and cancer-causing impacts of UV exposure.

Sources:

1. https://pubmed.ncbi.nlm.nih.gov/21079060/
2. https://www.epa.gov/sunsafety/health-effects-uv-radiation
3. https://www.epa.gov/sites/default/files/documents/uvradiation.pdf
4. https://www.skincancer.org/press/the-skin-cancer-foundation-shares-winter-sun-protection-tips/
5. https://apps.who.int/iris/handle/10665/42459
6. https://www.skincancer.org/press/the-skin-cancer-foundation-shares-winter-sun-protection-tips/