[en] The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) continuously evaluates the worldwide levels of occupational radiation exposure for two broad categories of sources: natural sources of radiation and man-made sources of radiation. The UNSCEAR evaluation is based on data from the UNSCEAR Global Survey of Occupational Radiation Exposures conducted by formal request to all 192 Member States of the United Nations, supplemented with data from literature. The UNSCEAR evaluations need to provide information relevant for policy and decisions regarding the use and management of radiation. The UNSCEAR questionnaire is designed in order to obtain the basic data to evaluate the level of occupational exposure in each sector and sub-sector of work. Specific additional information is requested for each sector or subsector and category of worker; as well as information to evaluate the reliability of the data. The UNSCEAR questionnaire is in good agreement with currently updated national databases. Since these databases for occupational exposure are the main source of information for UNSCEAR, they need to be regularly updated in order to reflect any change on the level of occupational radiation exposure when new technological developments and modifications to work practices occur. (author)