The assessment of UVA protection is a formidable problem, because sunlight is always a mixture of UVA and UVB, and the immediate and long-term effects of UVA are normally masked by the effects of energy in the more potent UVB wavelengths. Separation of UVA effects from those of full-spectrum UV is difficult, and :§ eliciting measurable responses to UVA alone requires high energy doses and relatively long exposure times.
Proposed human in vivo methods for assessing UVA protection include the immediate pigment darkening (IPD) method, the persistent pigment darkening (PPD) method, and the protection factor A (PFA) method. While each has its advantages, none is completely adequate for assigning a clinically relevant index of sunscreen protection in the UVA region.
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Rosacea and Eczema are two skin conditions that are fairly commonly found throughout the world. Each of them is characterized by different features, and can be both discomfiting as well as result in undesirable appearance features. In a nutshell, theyre problems that many would want to deal with.