Protecting the skin from the environment has been a practice since ancient times. Extracts of rice, jasmine, and olives were used by Egyptians, Greeks, and Indians to protect their skin from the environment. Their beauty rituals and habits paved the way for the invention of tanning oils and sunscreens.
In the modern-day world, UV filters are used to protect the skin against the damaging effect of sun rays. The UV filters used in making sunscreens are broadly categorized into two classes – chemical or organic filters and physical or inorganic sunscreens. And accordingly, sunscreens are categorized as physical/inorganic and chemical/organic sunscreens. Both physical and chemical sunscreens have different mechanisms of action in mitigating the damaging effect of UV rays on the skin. Before we talk about the mechanism of action it’s important to know of the different UV rays and how deep they can penetrate the skin layers. Some of the cellular changes that happen due to the damage are a generation of free radicals including both reactive oxygen species and reactive nitrogen species and the formation of DNA adducts. Eventually, the repetitive occurrence of these changes develop mutations that lead to the development of cancer.
Figure:1 Different types of solar rays and their ability to penetrate skin layers. 1
What are the different types of solar radiations and how do they damage the skin?
Solar radiation has UV rays ( UVA, UVB, UVC), visible light, and IR rays. Visible light is seen, IR rays are felt as heat, and UV rays cannot be seen or felt until the damage is done. Visible and infrared on their own have a small effect on skin damage but their potency is increased dramatically when UV is present. Of all the UV rays, UVC is filtered out by the ozone layer and does not reach the earth’s surface. UVA, UVB rays reach the earth’s surface and excessive unprotected exposure to these rays can damage the skin. Both UVA and UVB rays can penetrate into the skin layers. UVA rays account for 95% of UV rays and can penetrate the dermis. They are less intense but more damaging compared to UVB rays. UVA rays cause genetic damage leading to skin cancer and premature skin aging. UVA rays can also penetrate through glass ( windows, glass doors, etc) and hence it’s recommended to wear sunscreen if one is sitting close to an uncovered glass window or driving. UVB rays on the contrary can penetrate only the epidermis and cause sunburn, tan, inflammation, and blisters. These rays cannot penetrate through the glass.
Visible and IR rays can cause surface as well as damage to the deeper layers of the skin. It may cause inflammation and lead to loss of elasticity in the skin.
HEV/ blue light – This radiation is emitted from the sun and from electronic devices such as tablets, phones, computers, and television. They can penetrate the deeper skin layers with the potential to cause irreversible damage to the skin.
Figure 2: Effect of Hev/blue light on the skin. 2
How to protect the skin from UV rays and reduce the risk of skin cancer?
Physical shielding of the skin is the best way of protecting the skin from UV rays. This involves covering your body with clothes and wearing a wide-brim hat. UV-resistant clothing is available from many companies such as Patagonia, and Coolibar which can be an option too. If possible try to stand in the shade when outdoors or avoid outdoor activities between 10.00 AM and 4.00 PM when the intensity of rays are at peak.
Use sunscreen such as Trouvaille Sunscreen SPF 30 UVA/UVB – MONAESI (monaesiskincare.com) with SPF protection of 30 or above. If spending more than two hours in the sun, reapply sunscreen every two hours and if spending in water use a water-resistant sunscreen. The type of sunscreen used and the ingredients present in the product also have an effect on how the skin is protected.
References:
Journal of Dermatological Science, Vol: 85, pg 152 – 161, 2017
Harvard Education