1. What is an ultraviolet protection factor and how is it assessed?
An Ultraviolet Protection Factor (UPF) shows how much solar ultraviolet radiation (UVR) is reduced when passing through fabric of clothing. It is similar to the sun protection factor (SPF) used for sunscreens. The higher the UPF value, the lower the UVR penetration and the better the protection against sunburn.
An UPF is assessed in the laboratory under controlled conditions using an optical instrument called a spectrophotometer, which provides a direct measurement of UVR penetration. A British Standard (BS EN 13758-1:2002) describes the test method for clothing fabrics; another (BS EN 13758-2: 2003) describes the classification and marking of sun-protective clothing. Only clothing with UPF of at least 40 can be labelled as solar UV-protective according to the standard. Factors that contribute to the UPF rating are as follows:
2. What is considered a safe level of ultraviolet radiation exposure?
Ultraviolet radiation (UVR) is strongly linked to the induction of skin cancers, and probably to eye disorders, in particular cataract, and suppression of the body’s immune system. We live in an environment where UVR is usually present, the main source of exposure coming from the sun. It is believed that any UVR exposure is associated with an increased individual risk of these health effects. Scientific studies cannot demonstrate that there is a completely safe level of UVR exposure. At work, guidelines are set for UVR exposure to the skin and the eyes based on acute effects, such as skin redness and burning and inflammation in the outer eye. These guidelines are prepared assuming that all individuals are repeatedly exposed. Their aim is to prevent acute effects in this worst case situation, but they do not represent a line between safe and hazardous levels. UVR exposure does have beneficial effects, such as in vitamin D synthesis or in medical treatments for skin and other diseases. In the former, relatively low levels of UVR exposure are required and, in the latter, the exposures are controlled to maximise the beneficial effects of treatment.
Ultraviolet (UV) radiation
What is ultraviolet (UV) radiation and why is it dangerous?
UV radiation is invisible, high-energy radiation from the sun. It isn’t like the sun’s light which we can see or heat which we can feel. By the time you can feel sunburn, your skin has already been damaged. UV is the main cause of sunburn, tanning, premature ageing and skin cancer.
It wasn’t hot, so why did I get sunburnt?
The sun’s ultraviolet (UV) radiation – not heat – is the main cause of sunburn and skin cancer. It’s a myth that high temperatures are to blame. There can be high UV even on cool and cloudy days. And UV and temperature usually peak at different times of day. That’s why it’s important to pay attention to the sun protection times based on the UV levels rather than relying on temperature.