Window Glass and UV Rays: Protecting Your Skin from Harmful Exposure

Sunlight filtered through windows is not healthy for humans. In fact, it can actually be harmful and increase the risk for skin cancer from UV-A exposure. UV-B radiation is the beneficial form, and common window glass filters these rays.

UV-A Radiation

• Sunlight creates two types of ultraviolet radiation -- A and B. UV-A is the "tanning" rays and responsible for darkening the skin.

UV-B Radiation

• UV-B rays are superficially damaging, and they are more likely to cause sunburns. However, UV-B radiation is critically important to humans. It stimulates the production of vitamin D and melanocytes that produce melanin to protect the skin from UV-A.

UV-B and Windows

• Most UV-B rays cannot penetrate windows, and thus you do not receive their healthful benefits from light filtered through a windowpane. Experts recommend taking a vitamin D supplement if you are not getting enough sunlight, particularly in the winter.

Skin Cancer Risk

• Ordinary windows do not filter UV-A rays, and they are the most harmful in terms of causing skin cancer. This type of radiation penetrates the skin more deeply. Prolonged exposure to UV-A will also cause premature aging of the skin.

UV-A Filtered Windows

• Because of rising skin cancer rates, it is becoming more common for all types of windows to be made with either with UV-A filtering film or low-emittance coating, another type of UV filter.