 This TLV is supported by the International Commission on Non-Ionizing Radiation Protection and is used in setting lamp safety standards by the Illuminating Engineering Society of North America.When the Tuberculosis Ultraviolet Shelter Study was planned, this TLV was interpreted as if eye exposure in rooms was continuous over eight hours and at the highest eye-level irradiance found in the room.In those highly unlikely conditions, a 6.0 mJ/cm2 dose is reached under the ACGIH TLV after just eight hours of continuous exposure to an irradiance of 0.2 μW/cm2.