Using a daily face cream with SPF has become widespread practice. It’s recommended to apply sun protection on both sunny and cloudy days. But why is it so important to use products with SPF in your skincare routine, regardless of the weather? Why is the sun so dangerous for our skin?
Why should you protect yourself from the sun?
The sun emits electromagnetic waves that can be classified into different categories according to their wavelength: ultraviolet (UV) rays that are invisible to the eye (100 to 400 nm), visible light (400 to 700 nm) and infrared (700 nm to 1000 μm). Within the UV class, there are three subcategories: UVA (315 - 400 nm), UVB (280 - 315 nm) and UVC (100 nm - 280 nm). UVC rays, the most powerful, are the only ones that do not reach us, as they are stopped by the ozone layer.
5% of UV rays are UVB, which are responsible for tanning but also for sunburn and the majority of skin cancers because they are able to penetrate the epidermis, where they activate the synthesis of melanin, the pigment that determines your skin’s color. So, tanning is actually your skin’s defense mechanism, to protect it from the sun.
The intensity of UVB rays varies according to a few parameters: the closer we get to summer, the more we’re exposed between 11am and 3pm, the closer we are to the Equator and the higher the altitude, the more the sun’s rays will be intense and dangerous.
The other 95% of UV rays are UVA, which are able to more deeply penetrate your skin and reach the dermis. They can cause serious damage by directly altering your skin’s compounds, such as collagen and elastin fibers, which are responsible for your skin’s elasticity and tone. They can also cause genetic mutations in your cells’ DNA, and even cause cells to die.
In other words, UVA rays cause premature skin aging, in the form of pigmentation marks, loss of elasticity, dehydration, and the appearance of fine lines and wrinkles. UVA rays are present at all times of day, in winter as well as summer and, unlike UVB rays, can even penetrate through windows. This is why it’s important to take precautions to protect yourself as much as possible from UV rays.
The best way to protect yourself?
Our skin’s worst enemy is the sun. It accelerates skin aging and contributes to the development of certain cancers. Prolonged and repeated exposure to the sun is always risky, which is why it’s so important to protect yourself every day by applying a product with sun protection factor (SPF), especially in the areas most exposed to the sun.
Even if the sun has certain benefits (antidepressant, vitamin D production, etc…), it also has harmful side effects (photo-dermatosis, photo-aging, photo-carcinogenesis) caused by UVA and UVB rays. A sun protection cream is the best way to protect your skin from the harmful effects of the sun’s rays. Its effectiveness depends on the ultraviolet filters that it contains: the organic/chemical compounds and the mineral/physical compounds. Mineral/physical filters work by reflecting and diffusing UV rays, whereas organic/chemical filters help by absorbing UV rays.
Our skin types don’t all react to the sun in the same way. According to our phototype, our skin will react differently to sun exposure. Generally, dark skin (phototype 6) is less prone to sunburn, whereas very pale skin (phototype 1) is more sensitive and vulnerable. However, no matter what your phototype, it’s always important to use sun protection. And, even though sun protection cream plays an important role in protecting your skin from the sun, it’s also key to take certain precautions to reduce the risks:
Reduce your exposure to the sun, especially during the hottest hours of the day, from 11am to 3pm;
Wear sunglasses, a hat, and clothes which cover your skin;
Reapply your sun protection cream every 2 hours;
Use your sun protection daily, even on cloudy days, to help prevent skin aging.
BUABBAS H. & al. Photoprotection: clothing and glass. Dermatologic Clinics (2014).
WHITEMAN D. & al. Cancers in Australia attributable to exposure to solar ultraviolet radiation and prevented by regular sunscreen use. Australian and New Zealand Journal of Public Health (2015).
LIM H. W. & al. Sunscreens: An update. American Journal of Clinical Dermatology (2017).
LINOS E. & al. Sunscreens, cancer, and protecting our planet. The Lancet Planetary Health (2018).
WHITEMAN D. C. & al. How many melanomas might be prevented if more people applied sunscreen regularly ? British Journal of Dermatology (2018).