the present disclosure relates to polymeric siloxane coated zinc oxide powders having a mean particle size number distribution ranging from about 300 nm to about 600 nm and their use in sunscreen compositions . the relatively high surface area avoids agglomeration resulting in ease of formulation and high dispersal of the particles which tends toward less light scatter and hence better transparency in formulations . furthermore , the combination of the particular particle size number distribution of zinc oxide ranging as above with bistriazine uv absorbers shows unexpected increased uv - a absorbance in comparison to the zinc oxide and bis resorcinyl triazine uv absorbers on their own at the same concentration .