The external exposure control systems in KEK and CERN are discussed to nd out good practices and unreasonableness of radiation control in accelerator facilities, which plays an important role in optimizing national and/or site speci c radiological regulations, referring to relevant ICRP publications. Personal dose limits and radiation area classi cations were analyzed and their reasonableness were explored. Good example of supervised areas, area classi cation based on realistic assumptions on working time .etc are found. On the other hand, unreasonable systems, that are often attributed to the national regulation or ideas presented in the old publications are also found.