Ralph H. Thomas and G. R. Stevenson and W. P. Swanson and S. V. Thomas have comprehensively reviewed the production of radioactivity in air. The principal source of radioactivity in air at accelerators results from the interaction of primary and secondary particles directly with the constituent target nuclei in the air in accelerator enclosures. Airborne radioactivity releases can also be reduced by requiring long pathways from the point of production to the ventilation “stacks,” allowing time for radioactive decay to occur in transit, and by minimizing air gaps in the beam. A consideration concerning airborne radioactivity is that associated with the dose delivered to members of the general public when radionuclides are released to the atmosphere external to the accelerator enclosure. The airborne radioactivity hazard must be assessed both for workers exposed to airborne radio nuclides at accelerators and for members of the public who are exposed to effluents containing radio nuclides.