Several studies highlighted the danger of ultraviolet (UV) irradiation to the human body. Indeed, plenty of biological damages are induced by UV light source and adapted protections are required in order to reduce them.
This work presents the different sun protection assessment brought by sunscreens, fabrics and lenses. In each case, a specific name and method has been developed with, respectively SPF (Sun Protection Factor) for sunscreens, UPF (Ultraviolet Protection Factor) for fabrics and E-SPF (Eye- Sun Protection Factor) for lenses.
The best technique for reducing UV exposure is to avoid sun exposure, but this is an unacceptable solution to all. Fortunately, different ways for sun protection can be used such as sunscreens, fabrics and lenses but a combination of them is recommended. Historically, the concept of Sun Protection Factor (SPF) was introduced in the 1960s and has become a worldwide standard for classification of UV protection efficiency against erythema.1 Evaluation for the level of UVB protection has been historically based on in vivo method even if for ethical, practical and economical reasons it is not the best way. The in vivo sun protection assessment is carried out by measuring the minimal erythemal dose (MED) which consists of comparing the UV radiation dose required for the appearance of a first unambiguous biological endpoint, in this case skin redness, with and without the skin protected.
Nowadays, it is well known that products must be used to protect against sunlight damage by absorbing or scattering UV radiation and as much in the UVB as in the UVA (solar spectrum range 290-400 nm). Regarding UVA-PF (UVA Protection Factor) assessment, in vivo method used the PPD (Persistent Pigmentation Darkening) information in order to measure the UVA protection level. Reproducibility of in vivo sun protection assessment could be improved by four key parameters which must be respected: balanced volunteer panels with majority of I, II and III skin type response; careful application of sample (for example rate application and spreading method for sunscreen); controlled light source with UV SSR source (or PPD source for UVA); reproducible MED (or PPD for UVA) reading with first redness (or blackness for UVA) most of the time evaluated by human eyes after training.
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