Pseudomonas aeruginosa were enumerated on Pseudomonas Agar Base (CM 559, Oxoid) supplemented with fucidin, cephaloridine in 100 ml of distilled water and were homogenized by ultrasonication for 5 min. The obtained dispersion was filtered with a filter paper and the first 10 ml was rejected. Then 2 ml of filtered solution was adjusted to 50 ml using distilled water. The absorbance of each sample was determined by spectrophotometry in the range of 290–320 nm (UVB), with 5 nm intervals, using distilled water as blank. A fresh sunscreen sample (not submitted to temperature effect) was used as control, in order to establish initial SPF. Three replicates of each group were performed.