UV Rays in a Nutshell
Think back to the color wheel in your grade school art class or that rainbow you saw last summer. All of the colors we can see (red, orange, yellow, green, blue, indigo, violet, and all their various mixtures) make up visible light. Visible light is just one portion of the electromagnetic spectrum that ranges from long, low energy waves like radio waves all the way up to short, highly energetic waves like x-rays and gamma rays. “UV” stands for “ultraviolet.”
Ultraviolet rays are just beyond the violet end of the visible spectrum and are more energetic than visible light. Some animals (like bees) can see them but they are beyond the range of what the human eye can detect. The sun emits light at all different wavelengths, but it is ultraviolet rays that can cause sunburns. For more information on ultraviolet waves, visit the NASA website.
UV Rays, your Windows and your Home
Gases in our atmosphere like ozone can block much of the ultraviolet light that comes from the sun, but because of the increased elevation here in Colorado, there is less atmosphere between the ground and space, which means more UV light gets through. Depending on what elevation you are at this additional UV light can be as much as 25% more compared to that at sea level. This high concentration of ultraviolet rays can cause vinyl windows to damage, discolor or fading at altitude. A chemical called titanium dioxide can be used to treat vinyl windows to help prevent UV damage. Titanium dioxide can be a bit expensive, so most window manufacturers don't usually include the option but can really help prolong the life of your windows when high UV exposure is a concern. In addition, manufacturers that use titanium dioxide coatings often provide warranties against discoloration.
Ultraviolet light can be further broken down into ranges called UVA rays and UVB rays. UVA rays are more energetic than UVB rays and penetrate the skin more deeply. This type of ultraviolet light is used in tanning beds and has been shown to cause skin cancer. UVB rays can also cause skin cancer, but that part of the spectrum is primarily responsible for the actual burn when you get sunburnt.
According to the American Cancer Society, normal glass blocks UVB rays but unless otherwise treated, lets UVA rays pass through. Though these rays don't pose a significant danger to people unless they spend long amounts of time in direct sunlight, they can cause materials like fabrics to fade. Luckily, windows can be tinted or treated to prevent up to 99% of UV rays from entering your home.
When you are looking to buy new windows (especially at high altitude) check to see if they are treated to fend of UV rays. Titanium dioxide is a good option to protect the windows themselves and treated glass can prevent UV rays from entering. A few extra dollars up front could add years to the life of your windows and help to protect the people and possessions inside your home.