Why you should wear sunscreen even in winter

Guest article by Dr. Sarah Schunter 

Sun protection is often only associated with the hot summer months. But sunscreen is also essential in winter to protect against UV radiation. The skin remains vulnerable to the harmful effects of the sun all year round, especially UVA rays, which are also present in the cold season.

overview

• Why is sun protection necessary in winter ?
• How do UVA rays affect the skin?
• Sunscreen in winter: when to use it ?
• Which UVA protection should you wear in winter?

Why is sun protection necessary in winter?

Even though the sun often hides behind clouds and temperatures drop during the winter months, UV radiation remains a constant threat to the skin. The greatest danger comes from UVA rays , which account for 90-99% of the UV radiation reaching the earth's surface (1).

While UV-B rays decrease significantly in winter, UV-A radiation intensity fluctuates less throughout the year. Although these are also reduced compared to summer, they are still present (see Fig. 1) - enough to damage the skin.

Fig. 1., Diurnal variations of UVB (solid line) and UVA radiation (dotted line) in 1994, measured in Durham, UK. Adapted from Diffey BL et al., 2022 (2).

It is particularly important to remember the cumulative effect of UVA radiation, i.e. the radiation that accumulates on the skin over time and, taken together, can have a damaging effect on the skin. For example, it can be particularly insidious that UVA rays can also penetrate clouds, windows and even clothing. While many people actively think about sunscreen in the summer, protection is often neglected in the winter, which can continually damage the skin. UVA radiation can also reach the skin during short walks or through the windows of offices and cars.

How do UVA rays affect the skin?

UVA rays act on a cellular level. They promote the formation of free radicals, which cause oxidative stress and attack skin cells. This process accelerates skin aging and can lead to long-term damage such as DNA changes that increase the risk of skin cancer - again important here: cumulative UV exposure.

In addition, UVA rays can damage the connective tissue as well as the elastin and collagen fibers in the skin, which leads to a loss of elasticity and tone. Other signs of premature skin aging (photoaging) can also be attributed to UVA rays: pigment-related skin changes such as age spots and melasma. Last but not least, the oxidative effect caused by UVA radiation can inhibit the activity of immune cells, which can subsequently affect our immune system or manifest itself in increased inflammation of the skin (3).

Sunscreen in winter: when to use it?

It turns out that even in winter, the daily use of sunscreen should be an integral part of your skin care routine. Sunscreen should be worn in winter especially when

• the UV index rises above 3 during the day,
• You are outside during the day or
• for example, sitting in a light-filled room at work.

This is how you effectively protect your skin from the harmful effects of UV radiation all year round.

Which UVA protection should you wear in winter?

Not all sun creams in Germany and Europe explicitly state that they offer UVA protection. However, if the UVA circle symbol is shown on the packaging, you can assume that the sun cream's UVA protection is at least a third of the UVB protection ( SPF ). With an SPF of 30, this would therefore be at least a UVA protection of 10.

Theoretically, you can use products with lower UVB protection in winter, but the UVA protection may also be lower with an SPF of 30. It is therefore advisable to use a sunscreen with SPF 50 or to choose sunscreens that explicitly claim high UVA protection .

The following applies to the use of sunscreen in winter:

• All exposed skin areas, such as the face, neck, ears and hands, should be carefully protected with sunscreen.
• Sun protection should be taken into account, especially during outdoor activities such as skiing or hiking, as snow reflects up to 80% of UV radiation and can therefore significantly increase the radiation dose.
• It is important to give the sunscreen about 20 minutes to form a film. This will ensure that an even protective film of sunscreen forms on the skin.
• Make sure to reapply sunscreen every two hours, depending on your activity and the length of time you spend outdoors.
• Use a lip balm with sun protection to protect the sensitive skin of your lips from UV rays.
• A rich moisturizer or sunscreen product that provides moisture and protects against the cold is especially suitable for dry and sensitive skin types.
• When combined with other care products, sunscreen should always be applied last to ensure its effectiveness.

Conclusion

Sun protection is also important in winter to protect the skin from UVA radiation. UVA radiation penetrates the skin much more easily and deeply and can cause photoaging, pigment changes and long-term skin damage (including skin cancer). Therefore, make sure to wear sunscreen in winter too - ideally with sufficiently high UVA protection.

---

About the author

Dr. Sarah Schunter

Biochemist, scientific content creator (Instagram: @eattraincare ) and co-founder at 25SEVEN .

For over 10 years, Sarah has been writing about nutrition, sport and skin care from a scientific perspective - three topics that go hand in hand when it comes to feeling good in your body and skin. As a consultant and scientific content creator, Sarah supports skincare brands in optimizing their products and scientifically sound communication measures.

---

Sources:

(1) Narayanan DL, Saladi RN, Fox JL. Ultraviolet radiation and skin cancer. Int J Dermatol. 2010 Sep;49(9):978-86. doi: 10.1111/j.1365-4632.2010.04474.x. PMID: 20883261.

(2) Diffey BL. Sources and measurements of ultraviolet radiation. Methods. 2002 Sep;28(1):4-13. doi: 10.1016/s1046-2023(02)00204-9. PMID: 12231182.

(3) D'Orazio J, Jarrett S, Amaro-Ortiz A, Scott T. UV radiation and the skin. Int J Mol Sci. 2013 Jun 7;14(6):12222-48. doi: 10.3390/ijms140612222. PMID: 23749111; PMCID: PMC3709783.