It is safe and harmless to use 222nm far UVC for disinfection at a dose that meets the requirements of the specification. A series of animal and human experiments in academic institutions such as Columbia University have proved that far ultraviolet rays are safe for humans and mammals at a dose of 500mJ/cm², without causing skin cancer or cataracts. ACGIH has raised the skin exposure limit value of 222nm far-UVC to 479mJ/cm².