- You won’t get sunburned indoors because most types of glass block out UVB rays, which is the kind of UV light that causes burns and tans.
- But glass doesn’t block most UVA rays, which are the cause of sun damage, wrinkles, and even cancer.
- You can buy special tinting for your car and home windows that offer protection from UVA light.
- This article was medically reviewed by Debra Jaliman, MD, a board-certified dermatologist with a private practice in New York City.
- Visit Insider’s Health Reference library for more advice.
Most of us know to wear sunscreen when we’re outside in the sun, but you may need to take the same precautions when driving for long periods or sitting next to a sunny window at home.
Here’s what you need to know about how you can protect yourself from the sun’s rays, even when you’re indoors.
How you can get sun damage indoors
Sun damage happens when your skin is exposed to UV rays from the sun. There are two types of harmful UV rays:
- UVB rays, which cause tanning, sunburn, and skin cancer.
- UVA rays, which penetrate deeper into the skin, damaging collagen and causing ageing, wrinkling, and cancer.
Most types of glass block out UVB rays but not UVA. That means your skin won’t get burned from sitting in the car for a long drive on a sunny day. But you may still get harmful skin damage from the UVA rays that penetrate your car window. Remember, just because you can’t see the damage, doesn’t mean it isn’t there.
“People often have a false sense of security in their cars or behind windows since the UVB rays that cause a quicker sunburn are blocked,” says R. Sonia Batra, MD, a dermatologist in Santa Monica, California. “However, the UVA rays that penetrate glass actually reach a deeper layer of skin and still cause sun damage, discoloration, and wrinkles,” Batra says.
Some windows are more protective than others
Car windshields are made out of laminated glass, meaning that there is a layer of specialised plastic between two glass layers. This plastic allows the glass to stretch and easily break, and also completely blocks UVB rays and about 96 per cent of UVA rays
So you don’t need to worry about getting skin damage through a car’s front window. However, the car’s side windows are a different story.
Side windows are made from tempered glass, which has no plastic layer. The glass still blocks nearly all UVB rays but it only blocks 71 per cent of UVA rays, on average. And in some cars, it blocks as little as 44 per cent of UVA rays.
For long periods of driving, this is not enough to protect against skin damage from UVA rays, and the prevalence of skin cancer in drivers proves it. A 2010 study found that Americans who spent more time driving were more likely to develop skin cancer on their left side – the side that is closest to the side window.
In this study, 53 per cent of participants developed skin cancer on the left side of their face, while 47 per cent had cancer on the right side. Malignant melanoma, the most serious type of skin cancer, was even more divided, with 74 per cent of cases on the left side and only 26 per cent on the right.
Windows at home and at work are also not entirely protective. “Both car and home windows block shorter UVB rays that cause sunburn”, Batra says, “but longer UVA rays still pass through.
If you are just sitting in a room lit by sunlight, you are not likely to get sun damage, but if you are positioned next to a window getting direct sunlight for many hours of the day, you may want to take precautions.
How to prevent getting sunburned indoors
If you will be spending a long period of time in front of a window at home or at work, you can use a broad-spectrum sunscreen to protect exposed skin. Broad-spectrum sunscreens protect against both UVA and UVB rays.
“I usually recommend a mineral-based, physical sunscreen with zinc oxide or titanium dioxide and at least an SPF of 30,” Batra says. Mineral sunscreens may be preferable to chemical sunscreen because they are less likely to irritate your skin.
You can also add a clear protective film to your window that filters out UVA rays, Batra says. Studies show that UV protective films, which can be found at many hardware stores, can reduce UVA transmission by more than 99 per cent.
You can also add protective film or tint to your car windows to block out UVA light, but first check up on your local laws, as some states place restrictions on window tints.
Though you are unlikely to get sunburned through a car or home window, you may still be exposed to harmful UVA rays that can accelerate skin ageing and increase the risk of skin cancer. Protect yourself with a broad-spectrum sunscreen or use a window film if you plan to spend a lot of time in the car or by a window.
Related articles from Health Reference:
- What is sun poisoning and what makes it different from sunburn
- The causes of dry skin, from hot showers to winter weather
- Vitamins A, B, C, and E are good for your skin
- Why you should never treat a sunburn with vinegar
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