Should I Wear Sunscreen Indoors?
by Claudia Christin on Mar 21, 2023

The sunβs far from our eyesight, we are indoors and the sun does not shine on top of our head directly. Has it ever come to your mind whether it's the perfect time to skip on your sunscreen. Itβs normal for anyone to think so, having the thoughts that they can save so much money to not wear sunscreen on cloudy days or indoors! Oh well, but itβs not the case for everyone and we are going to dig in deeper on the pros and cons of skipping your sunscreen while youβre indoors.
First, we should clearly understand that the sun is the number one risk factor of premature aging and sunscreen protects us not from the aesthetic side of it, but it is also protecting us from prolonged exposure risk for skin cancer. Letβs answer each one of your commonly asked questions related to sunscreen and being indoors:

Q: βIf the cloud is out, sun is hiding, and we are indoors,Β
the UV rays will have no chance to reach us, right?β
Answer: Actually, the UV rays can still pass through the clouds, and it is still able to pass through the window as well, especially the UVA rays. 50 - 60% of the UVA can pass through and lead to premature aging. However, the number may differ depending on the thickness or the type of technology the embedded on the window, but most of them canβt entirely filter through the UV rays.

If you are not sure whether to use sunscreen or not, check the weather apps to see the UV index! If the UV index number is shown to be around 1-3 you can skip sunscreen (this applies even when youβre outdoor).. However, if the UV index number is shown to be above 3, your skin definitely would thank you if you wear sunscreen indoors, especially if you are doing activities near the window.
It is also advised to pay attention to often forgotten body part in times like this, such as hands, neck, and decolletage. Since the hand, neck and decolletage are often neglected even though they are exposed to the sun as much as our face, many experience premature aging on those areas sooner than the other parts of skin they take care of.

Q: βI donβt even notice my skin being darker if I donβt wear sunscreen indoors. Whatβs the importance of wearing sunscreen when Iβm indoors then?β
Answer: Because actually, glass windows do filter out UVB rays β which plays a huge role in burning our skin, hence why we do not feel our skin to be darker if we do not wear sunscreen indoors. However, glass windows can not filter out UVA rays - which plays a huge role in aging and hyperpigmentation. The impact of UVA exposure may not show right away at the moment, but it gradually builds up and as time goes by, youβll notice your skin aging earlier than it should. The UVA rays penetrate to the deeper layer of your skin and the damage is just as harmful to your skin. This is why you are still recommended to use sunscreen even indoors.

UVA |
Both |
UVB |
Aging |
Cause skin damageΒ |
BurningΒ |
Longer wavelength and reaches to deeper layer of our skin |
Penetrate through cloudsΒ |
Shorter wavelength and are responsible for surface damageΒ |
Responsible for signs of aging and accumulative damageΒ |
Causes immediate sunburn and other skin damageΒ |
|
Can penetrate through glassΒ |
Canβt penetrate through glassΒ |

Q: βWhat if Iβm entirely indoor without any single bit of sun exposureΒ
(I'll close the blind and all)β
Answer: If youβre entirely indoors with no sun exposure at all through the windows, of course you can skip the sunscreen without having to be worried about it. However, most of the time you may have to get yourself out and expose yourself to a little bit of sun, either if itβs taking your takeaway or doing a little grocery shopping. Even when youβre inside your car, the UVA rays can still cause damage to your skin cumulatively.

Q: βOkay, Iβll use sunscreen even indoors from now on.Β
But do I need to reapply?β
Answer:Β Reapplying every 3-4 hoursΒ is not a mustΒ because we are less likely to be sweating indoors so it should be still staying in place and not be erased easily. But it doesnβt mean that you are not allowed to reapply, it is still best to reapply especially if you are next to the window, but maybe the amount of time youβre reapplying shouldnβt be as often as if you are outdoors.
Tips when youβre indoor and you want to reapply:Β
Reapply 15- 30 minutes before noon (12 pm) with added physical protection since it is the time of highest UV intensity (index).