Although you might experience the sun differently in the summer than you do in the fall, winter, or spring, exposure to the sun's UV radiation is always dangerous. In order to maintain healthy skin and overall well-being, you need to wear sunscreen year round.
In addition to visible light, the sun produces UV radiation that reaches the earth in a variety of wavelengths, the most dangerous of which are UVA and UVB rays. UVA radiation is a longer wavelength that penetrates deep into the skin is primarily associated with skin aging. Though less powerful than UVB radiation, UVA poses serious cancers risk given that it makes up 95% of the total UV radiation that reaches the earth. UVA also penetrates cloud cover, glass, and reflects off of many surfaces. Snow, for example, reflects up to 80% of UV radiation. Compared to UVB, UVA radiation is more consistent from season to season, meaning that without the right sunscreen, you experience the carcinogenic, skin aging effects of the the sun year round.
UVB radiation has a shorter wavelength that only penetrates the outer layers of your skin. UVB is more powerful, less abundant, and associated with skin burning. A sunscreen’s SPF rating measures protection from the sun’s UVB rays. UVB is more intense in the summer, on clearer days, higher altitudes, and reflects off of surfaces such as snow and water. While UVB varies based on factors such as cloud cover, seasonality, and time of day, outdoor winter activities such as skiing that take place in high altitude, reflective environments can more than make up for the seasonal variation.
SPF is a measure of protection from UVB radiation. Dermatologists recommend SPF 30 or higher for prolonged activity under the sun. By definition, If you apply SPF 30 sunscreen correctly, it would take 30x more sun exposure to burn you than if you were not wearing sunscreen. When applied correctly, SPF 30 will block 97% of the sun’s UVB rays and SPF 50 will block 98%. While the right SPF 30 proves effective in most conditions, we choose SPF 50 for our most extreme environments. We don’t offer a sunscreen above SPF 50 because studies show that claims over SPF 50 are often inaccurate and give a false sense of security.
A sunscreens SPF rating, however, does not imply any protection from UVA radiation. The term, Broad Spectrum, refers to a sunscreen’s ability to protect from both UVA and UVB radiation.
You should pay as much attention to your sunscreen’s ingredients as SPF and Broad Spectrum claims. Minerals, Zinc Oxide and Titanium Dioxide are the only two sunscreen active sunscreen ingredients that the FDA has deemed Safe and effective. Mineral Sunscreens generally use one or both of these ingredients. On the other hand, sunscreens generally claim “Mineral-based” when they utilize a combination of chemical and mineral active ingredients. Among the most widely used chemical active ingredients, Octocrylene, Octinoxate, Avobenzone, Oxybenzone, and Homosalate absorb into your skin and bloodstream and cause a number of human and environmental health issues. Recent studies have uncovered links to cancer, hormone disruption in humans, marine, and terrestrial wildlife, as well as coral bleaching.