XPA and skin neoplasm: By contrast with our previous study showing an 80% incidence of skin tumors from broad‐band UVB exposure for Xpa‐knockout mice (0.25 kJ m−2, once a week) (21), we observed no tumors in any of the mice with 222‐nm UVC irradiation, indicating that 222‐nm UVC did not exert photocarcinogenic effects (Fig. 4).