Do UV rays pass through glass?

It may not be obvious, but UV rays can have a real impact on your skin even through glass windows. Ultraviolet radiation is an invisible energy emitted by the sun and includes three types of rays: UVA, UVB, and UVC (the latter do not enter the Earth's atmosphere).

UVA rays, which penetrate deep into the skin, are responsible for hyperpigmentation and cause visible signs of aging like loss of elasticity and wrinkles. UVA rays can pass through glass and even cloud cover ☁️, and are linked to an increased risk of skin cancer, although UVB rays (which cause sunburn) remain the primary cause. UVB rays are generally blocked by glass, and some types of glass can also reduce UVA rays. Laminated glass can nearly eliminate them altogether.

Here are two situations where your skin is particularly exposed to UV rays through windows and glass panes 🪟:

In the car 🚗: driving is one of the activities that significantly increases sun exposure. Hand aging due to UV rays is largely caused by the time we spend behind the wheel. According to a U.S. study conducted in 2016, windshields block about 96% of UV rays, while side windows only block around 71%. This means the side of the face closest to the window is especially at risk for skin cancer. In Australia, where the steering wheel is on the right side of the car, more cases of skin cancer are reported on the right side of the face.

If you spend a lot of time on the road, wearing a wide-brimmed UV-protective hat and UV-protective gloves or mittens can be a smart way to help protect your skin from the sun’s harmful effects.

At home 🏠 or in the office 💼: since the COVID-19 pandemic, more people have been working from home and spending more time indoors. At home or in the office, sunscreen is usually not necessary because UV exposure is limited. However, if you spend a lot of time near a window with direct sunlight ☀️, it’s worth taking some precautions. Not only can UV radiation pass through glass 🪟, but it can also reflect off various surfaces.