Glass in commercial buildings and vehicles can block a percentage of UV radiation, however the amount depends on the type of glass.
With vehicles there are a number of factors that influence the UV levels inside a vehicle such as whether windows are open or not, and the position of the vehicle in relation to the sun. The type of glass used in vehicles also determines the amount of UV reaching the inside of the vehicle. Laminated glass, used for windscreens, and tempered glass, usually used for side and rear windows, both block UV B radiation. However UV A radiation can still penetrate tempered glass, whereas about 98% of UV A is blocked by laminated glass due to its design.
The amount of UV A that can penetrate tempered glass can vary dependant on a number of factors including the thickness and colour of the glass. In some cases it has been estimated that up to 79% of UV A radiation can penetrate tempered glass.
Window films, both clear and tinted, can reduce UV radiation by over 99%, making it an effective preventative measures against UV radiation. In Australia each state has regulations that stipulate the maximum darkness of the tint, referred to as the visible light transmission level or VLT. However it is important to understand that the darker the tint does not necessarily increase the level of UV protection.
While it may seem obvious, window tinting is only effective when the window is up, and provides no protection when the window is down. If you have tinted windows on your vehicle you should keep your windows closed when the UV is 3 or above to ensure maximum protection.
Another alternative with vehicle windows is the use of fabric side window covers. Unfortunately the effectiveness of these is limited dependent of the quality of the product and as well as the fact that they only protect the small area they cover. If placed on one side window there is still the risk of UV radiation penetrating from other side or the rear window. For this reason tinting is considered a more effective and consistent method of protection from UV radiation.
As with vehicles, the level of UV A transmission through building glass is highly dependent on the type of glass. Laminated building glass reduces the transmission of UV A completely, whereas tempered and smooth annealed glass can allow up to 74% of UV A through.
Tinting of windows on buildings can further reduce the level of UV transmission however the risk and cost should be weighed up to the actual health risk. Generally UV radiation through windows of buildings pose little risk to people unless they are spending extended periods of time close to a window that receives direct sunlight, or they have a severe photosensitive skin disorder.
If you spend a lot of time in a vehicle when the UV is 3 or above window tinting can be an effective way to protect your from harmful levels of ultraviolet radiation. However tinting of buildings may not be required, dependant on the exposure to direct sunlight. It is important to understand where you are at risk, and if it is necessary to employ some protective measures or not.