The major radiological environmental impact of the Lawrence Berkeley Laboratory is due to the operation of four particle accelerators in the pursuit of fundamental research in various disciplines including biology, chemistry, medicine and physics. Potential sources of population exposure at the Laboratory are discussed. The major source of population exposure due to accelerator operation arises from the prompt radiation field which consists principally of neutrons and photons. Release of small quantities of radionuclides is also a potential source of population exposure but is usually an order of magnitude less significant. Accelerator produced radiation levels at the Laboratory boundary are comparable with the magnitudes of the fluctuations found in the natural background radiation. Considerable effort has, therefore, been expended in understanding the magnitude of the components of natural background at the Lawrence Berkeley Laboratory, so that the magnitude of Laboratory-produced radiation may be accurately determined. Environmental monitoring of accelerator-produced radiation and of radionuclides is carried on throughout the Laboratory, at the Laboratory perimeter, and in the regions surrounding the Laboratory. The techniques used are described. Finally, the models used to calculate population exposure are described and discussed.