Hyperbaric oxygen improves ultraviolet B irradiation-induced melanin pigmentation and diminishes senile spot size.

Background: The effects of exposure to hyperbaric oxygen on ultraviolet B (UVB) irradiation-induced melanin pigmentations of skins and on senile spot sizes of faces were investigated. Methods: In the first experiment, male subjects were irradiated with UVB on their upper arms for inducing erythema and the subsequent melanin pigmentation. They were exposed to a hyperbaric environment at 1.25 atmospheres absolute (ATA) with 32% oxygen for 1 h/day, three times per week. In the second experiment, female subjects were exposed to a hyperbaric environment at 1.25 ATA with 32% oxygen for 1 h/day, two times per week. Results: In the first experiment, melanin pigmentations lightened after 4 weeks of exposure to hyperbaric oxygen. In the second experiment, senile spot sizes became small after 12 weeks of exposure to hyperbaric oxygen. Conclusion: We concluded that exposure to hyperbaric oxygen used in this study accelerates both the fading in melanin pigmentation and the decrease in senile spot size.