The common opinion by dermatologists is that you should wear sunscreen indoors.
Why? If you're sitting near windows — or in front of a computer screen — you're exposing yourself to potentially skin-damaging light: Ultraviolet A (UVA), Ultraviolet B (UVB), both emitted by sun; and blue light emitted by smart devices, computers, and TVs.
UVB rays can damage the outermost layers of the skin and are responsible for producing sunburn.
UVA rays penetrate deeper into the skin and can cause genetic damage to cells. UVA plays a greater role in premature skin aging changes including wrinkle formation (photoaging).
Unlike UVB rays, whose intensity varies with seasons, UVA rays are potent year-round and penetrate clouds and glass.
Blue light emitted by our screens can increase the production of melanin or pigmentation in the skin, which could lead to melasma and age spots. Blue light can also create free radicals, which might cause inflammation and lead to the breakdown of collagen and elastic tissue in the skin.
You might think that staying indoor will protect you from UVA and UVB. The following case will, hopefully, convince you otherwise.
Bill McElligott’s case was published by The New England Journal of Medicine in 2012 and demonstrated 69-year-old's face after 28 years he has spent driving on the job. The left of the man’s face, the side that has been exposed to UVA rays through his delivery truck’s window, was visibly more damaged than the right side, which was not getting direct UVA, is relatively smooth by comparison. The man was diagnosed with dermatoheliosis, ie. photodamaged skin.
Chronic UVA exposure resulted in thickening of the skin's top layers, the epidermis and stratum corneum, as well as destruction of the skin's elastic fibers.
This case proves that glass will not protect you against damage unless covered with special protective film.
However, it doesn’t mean that you must wear sunscreen all the time at home, but if you want to sit near a window, or in front of a screen, remember the case (and the face) of Bill McElligott and apply sunscreen.
Sunscreen should be an essential part of your daily skincare routine, regardless of the season or your plans for the day. Your skin will thank you down the line.