Figure 2

The distibution of 25(OH)D level and relationship with cumulative dosage of UVB irradiation. (a) For all time-point irradiation; (b) at 3 w irradiation. The optimal mathematical function to describe the associations between UBV irradiation dosages and 25(OH)D level at 3 w was determined by maximal R square value. The optimal dosage of UVB (355 mj/cm2) to reach 25(OH)D level at 30 ng/mL was estimated based on the mathematical function.