Work rooms where the spatial and instrumental equipment enables safe handling of Radioactive substances which are not enclosed, i.e. surround.... Pursuant to IAEO recommendations, Atoms of the same atomic number (i.e. the same chemical elem... laboratories are classified in three types according to the Activity is the term used to characterise the number of nucl... which they are allowed to handle: A, B and C. In this context, measurement of Activity is the term used to characterise the number of nucl... is a multiple of the free limit in accordance with the Radiological Protection Ordinance. Laboratory type C thus corresponds to a handling quantity of up to 102 times, laboratory type B up to 105 times and laboratory type A beyond 105 times the free limit. In type C laboratories, fume cupboards are to be installed when there is a In risk comparisons in particular, a risk is frequently defi... of impermissible ambient air Unwanted pollution of working surfaces, devices, rooms, wate.... In general, exhaust air filtering is not required. In type B and A laboratories, provision is to be made for glove boxes or other working cells, in addition to fume cupboards, for the handling of Radioactive substances which are not enclosed, i.e. surround.... Exhaust air filtering is required. Details are contained in DIN 25 425.