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This is an often asked question - is sunscreen only for the outdoors or does your skin need to be protected when indoors too? The TL;DR of all this, of course, is that you need it when the sun is out - irrespective of whether you are in or out!
In order to understand why we need to understand not just sunlight but also sun science!
Evolution of skin science
Until recently, all sun science was geared towards UVB protection. SPF or Sun Protection Factor was developed when we did not fully understand UV-induced sun damage and it measures protection from only the UVB rays or sunburn. Simply put, SPF is the time taken to burn with sunscreen divided by the time taken to burn without sunscreen for a specified dose of UVB.
However, UVB rays account for less than 5% of solar UV rays. The remaining 95% of the UV component of sunlight comprises UVA radiation. These UVA rays also affect our skin adversely.
UVA and UVB
UVB rays cause instant redness and sunburn, while UVA radiation causes slow and constant skin damage and ageing. UVB rays are strongest around noon and during the summer and are absorbed directly by skin DNA resulting in instant sun damage. UVA radiation, on the other hand, is relatively constant all day through and present even on cloudy days. Due to longer wavelengths, UVA radiation also penetrates much deeper into the skin
UVB radiation cannot penetrate glass, and hence it does not have any effect indoors. UVA radiation makes up a large proportion of sunlight and can easily penetrate glass, making it a threat even when indoors!
Not only this, recent research reports also indicate that parts of visible light such as blue light from laptops, televisions, and mobile phone screens are also a cause of free radical damage and skin ageing.
So, wearing sunscreen indoors is a must, in order to protect your skin.
So what kind of sunscreen should you choose for indoor use?
As mentioned before, UVB radiation is not a concern indoors. So SPF is not important! Another interesting fact is that physical sunscreens are much more effective at blocking UVA radiation and blue light compared to chemical sunscreens. What you need indoors is high UVA protection as indicated by the PA ++++ ratings. PA ++++ is a rating system established in Japan that allows the users to know the level of protection a product gives against UVA rays. The general range of the rating is from PA + to PA ++++ - The Sandiva Sunblock is SPF 35 with PA ++++ (the highest rating for ultimate indoor sun protection).
If you want to take it a step further, a physical sunscreen tinted with iron oxides might offer the best combination as iron oxides have been shown to enhance blue light protection. While SPF is what we have traditionally looked at, the PA rating is what you should look for to protect your skin from UVA rays when both indoors and outdoors.
Sun protection science continues to evolve, and we must keep a watch on new information as it becomes available. For now, here’s our recommendation: Choose a sunscreen that provides broad spectrum protection, that has a moderately high UVB protection like SPF 30, and a high UVA rating (PA ++++).
Sandiva’s One and Done Tinted Sunblock is the one-stop solution for all your sunscreen needs. It is a physical sunscreen that gives protection against UV rays and blue light. What’s more, while other physical sunscreens leave a white cast, our creamy formula comes in different shades to suit all skin tones. So, protect your skin from sun damage, and blue light while looking radiant.
Your skin is not only your largest organ, but it is also an incredibly complex adaptive system that is your greatest weapon to combat the ill effects of solar radiation. Your skin is constantly repairing DNA and cellular damage caused by a wide variety of adverse stressors that we encounter as we go about our lives. The best thing you can do for your skin is to protect it - in other words, wear sunscreen both outdoors and indoors. Yes, you read it right! Let’s debunk the myth floating around about wearing sunscreen only when you’re outdoors.
To know more about the basics of sun protection, you can read Decoding Sunlight - Basics of SPF Protection