Can You Get Skin Damage From The Sun Indoors?
It’s pretty well-known that sun damage to the skin can occur indoors and in your car, but there are still people out there who feel a false sense of protection behind glass. This is partly due to people not knowing (or ignoring) the differences between UV-A and UV-B. You should know how much UV-B and UV-A actually get through for different types of glass, and how can and how should you protect yourself. Let’s start with the rays we want to avoid.
UV-B & UV-A
Two main types of ultraviolet (UV) rays from the sun can cause DNA damage in your skin, even from brief exposure. The shorter UV-B rays mainly cause sunburn, while the longer UV-A rays lead to tanning and skin ageing. Although UV-A rays are less likely to cause sunburn compared to UV-B rays, they can penetrate deeper into the skin, leading to premature skin ageing and potentially contributing to the development of skin cancer and many other skin issues. Most UV-B radiation is blocked by glass, but this is not the case with UV-A.
Driving
You can get sun damage from sitting in any type of vehicle, but most studies we found focus on the car driver. Plenty of studies have pointed to instances of sun damage and cancer while sitting in a car because it’s easy to quantify. Scientists can simply look at a person’s right or left arm or face and see that more damage occurs on the side next to the window. It has been proved that people tend not to realise that they are not protected behind glass while being in a car.
UV Rays Through the Car Windscreen
Luckily enough, front windscreens consistently provide high levels of UV-A protection. This is true across various car makes and models a study confirmed (1). The range of UV-A blockage from front windscreens is around 95-98% (1). As a rough guide, this would be similar to wearing SPF50. This protection is due to the construction of front windscreens, which contain a plastic layer sandwiched between two panes of glass. This design effectively filters out a significant portion of UV-A radiation, making sure that drivers and front-seat passengers are well-protected from the sun’s harmful rays. The story is a little different for the side windows.
UV-A From Car Side Windows
In contrast to the UV-A protection offered by the front windscreen, side windows provide significantly lower and more variable levels of protection. The average UV-A blockage from side windows is only 71%, with a wide range of 44-96%. This disparity in protection is due to the fact that side windows are typically made from a single pane of glass, which may or may not include UV-blocking components. It is important to note that tinted side windows do not necessarily provide high levels of UV-A protection, as the tint may be primarily designed for aesthetic purposes or to reduce glare.
The lower level of UV-A protection offered by side windows has implications for the health of drivers and passengers. Over time, the exposed side of the face and eye may be exposed to higher levels of cumulative UV-A radiation. This potentially explains the higher reported rates of cataract formation in the eyes and also skin cancer on the exposed side of the face. It would be prudent to find stats for your make and model.
The Sunroof
Overlook the chance that your sunroof is letting in rays at your peril. Credible but scientifically unconfirmed evidence suggests that sunroofs are no more protective than side windows. In theory only, older cars would fare worse than newer ones.
Indoors
In a thorough study (2), looking at UV-A through glass, commonly used glass was found to transmit UV-A, as much as 74%. The thickness of the glass was not statistically significant to the transmitted UV ray amount. So, when compared with car side windows, which block, on average, 71%, run-of-the-mill glass fares worse, at 26%. Be mindful when in places such as conservatories, and be aware of the dangers of being close to windows.
Don’t Forget Your Eyes
Another thing to remember is your eyes. UV radiation can cause damage to the eyes and could end up causing conditions such as cataracts, pterygium (a growth on the white of the eye), and even eye cancers. Yes, car windscreens offer a good level of protection, but side windows and sunroofs may allow more UV rays to reach your eyes. Wearing sunglasses with 100% UV protection can help shield your eyes from these harmful rays while driving or sitting in a car.
Your Hands Too
The backs of the hands, in particular, are often exposed to UV radiation while driving. This skin area is thin and delicate, making it more susceptible to sun damage and premature ageing. Applying a broad-spectrum sunscreen with an SPF of at least 30 to your hands before driving can help protect them from UV rays that penetrate the side windows and elsewhere.
What can you do?
There are several steps you can take to protect yourself from UV radiation while in your car or indoors:
- Apply sunscreen: Use a broad-spectrum sunscreen with an SPF of at least 30 on all exposed skin, including your face, neck, arms, and hands. Reapply every two hours or more frequently if you’re sweating or in direct sunlight for extended periods. SPF measures protection against UV-B rays. The “broad-spectrum” label on sunscreens indicates that the product also protects against UV-A rays.
- Wear protective clothing: Long-sleeved shirts, trousers, and hats can provide additional protection from UV rays. For even better protection, consider investing in clothing with a high Ultraviolet Protection Factor (UPF) rating.
- Install UV-blocking window film: Applying a UV-blocking window film to your car’s side windows and sunroof can significantly reduce UV-A radiation entering the vehicle. These films are also available for home and office windows. They typically cost around £10 or so per square meter.
As always, consult a clinic specialising in skin issues or a dermatologist should you have any doubts about something different about your skin. Perform regular skin self-examinations and use the ABCDE rule for identifying potential melanomas.
References
- Boxer Wachler BS. Assessment of Levels of Ultraviolet A Light Protection in Automobile Windshields and Side Windows. JAMA Ophthalmol. 2016;134(7):772–775. doi:10.1001/jamaophthalmol.2016.1139
https://pubmed.ncbi.nlm.nih.gov/27258091/ - Duarte, Ida et al. “The role of glass as a barrier against the transmission of ultraviolet radiation: an experimental study.” Photodermatology, photoimmunology & photomedicine vol. 25,4 (2009): 181-4. doi:10.1111/j.1600-0781.2009.00434.x
https://pubmed.ncbi.nlm.nih.gov/19614895/
