Yes, You Still Need to Use SPF Even When Indoors. Here's What Experts Recommend

Many overlook the ongoing risk of UV exposure and skip applying SPF or taking other measures to adequately protect their skin indoors. It's a common misconception that this is when you're safest from UV rays, but let's clear up any confusion. 

Whether indoors or out, proper sun protection remains necessary because UV rays enter your home through the windows. This prolonged sun exposure can lead to loss of skin elasticity, wrinkles, skin cancer and more, but regular sun protection can mitigate these risks, meaning healthier skin in the long run.

We'll explain why sun protection is important when indoors, along with expert advice on ways you can protect your skin year-round. 

Do you need to wear sunscreen indoors? 

Yes, wearing sunscreen indoors is necessary. Even though you're sitting comfortably in your home, UV rays can cause just as much damage to your skin as they would if you were sitting outside in your backyard. 

Since there are different types of UV rays, understanding how each affects you can help you understand why daily sun protection is important.

Here are the three main types of UV rays: 

• UVA (Ultraviolet A): UVA rays penetrate deeply into the skin, contributing significantly to skin aging and increasing the risk of skin cancer.
• UVB (Ultraviolet B): UVB rays primarily affect the outer layers of the skin, causing sunburn and playing a crucial role in the development of skin cancer.
• UVC (Ultraviolet C): UVC rays are absorbed by the Earth's atmosphere and do not reach the surface, thus posing no direct threat to human health.
  

According to Skin Cancer Foundation, window glass blocks most UVB rays but allows at least 50% of UVA rays to pass through. Prolonged exposure to these UVA rays indoors can contribute to premature skin aging and potentially increase the risk of skin cancer over time.

"In the short term, prolonged UV exposure increases the risk of developing a sunburn, which at its most extreme version can include systemic symptoms such as fever and chills," said Dr. Elyse Love, board-certified dermatologist. "Cumulative prolonged UV exposure is a leading cause of skin cancer development."

What type of sun protection do you need when sitting in front of a window?

If you're sitting in front of a window, sunscreen is always a great defense against UVA rays. Sun protection factor, or SPF, works by extending the time it takes for UV rays to cause sunburn on your skin compared to not using sunscreen. 

One of many myths about sunscreen is the higher the SPF, the better the protection; however, when it comes to daily sunscreen use for those indoors, a high SPF isn't necessary. "Broad-spectrum SPF 30 is adequate sun protection," said Love. 

Since sunscreen comes in different forms, including sprays, creams, lotions and gels, this will also factor into what works best for you. "I recommend considering personal preference of skincare textures and how practical reapplication of sunscreen will be," Love stated. 

Your clothing also shields you from the sun, but you'll want to ensure your ultraviolet protective factor or sun-protective clothing is sufficient. There are a few things to consider when it comes to factors like color, fabric and fit. 

For example, dark or bright colors absorb UV rays, offering better protection than lighter shades. Densely woven fabrics like denim, canvas, wool or synthetic fibers create a more effective barrier by preventing UV penetration. Then there are fabrics like unbleached cotton, shiny polyesters or high-tech materials with UPF labels that maximize protection, reflecting or absorbing UV radiation. Additionally, loose-fitting attire ensures fibers remain close, not stretched across the skin, enhancing overall coverage and effectiveness against UV exposure.

"For situations where reapplication will be difficult, but UV exposure cannot be avoided, I recommend UPF clothing, which provides steady protection while wearing," Love explained. 

Tips for sun protection indoors 

Window treatments enhance protection against UV rays indoors. Use window blinds, shades or curtains made from UV-protective materials to filter out harmful rays while still allowing natural light to enter. Also, remember to close window coverings during periods of intense sunlight, especially in rooms where you spend a lot of time. This practice not only reduces UV exposure but also helps regulate indoor temperature. 

"Lowering shades during peak sun hours (10 a.m. to 3 p.m.) can be very helpful to minimize direct UV exposure while indoors. In addition, positioning furniture so that the back is away from direct sun sources," said Love.

To mitigate these risks, you can also place UV-blocking films or coatings on windows. This provides additional protection by reducing UV transmission without compromising natural light indoors. According to National Glazing Solution, window film can successfully block up to 99.9% of UV rays. 

Too long; didn't read

Sitting in front of a window exposes you to UV rays, which can penetrate glass and cause skin damage. Taking proactive steps against indoor UV exposure not only guards against premature aging and skin cancer but also promotes overall skin health. 

Prioritizing sun protection -- whether through daily sunscreen application (at least broad-spectrum SPF 30), using UV-blocking window treatments or wearing sun-safe clothing -- ensures that your skin remains healthy. 

By integrating these practices into your routine, you can effectively minimize the cumulative effects of UV exposure and maintain optimal skin wellness indoors and out.