In vitro UVA PF and Critical Wavelength ISO 24443:2012 method

The ISO 24443 method specifies an in vitro procedure to characterize the UVA protection of sunscreen products in a reproducible manner. In order to determine relevant UVA protection parameters, the method is strictly followed to provide a UV spectral absorbance curve from which a number of calculations can be undertaken such as the UVA Protection Factor (UVAPF) and the Critical Wavelength (CW). This method relies on the use of in vivo SPF results for scaling the UV absorbance curve.