Objective: To propose a practical method for identifying workers potentially exposed to manufactured nano-objects, their aggregates, and agglomerates (NOAA) and to characterize their potential exposure within the EpiNano epidemiological surveillance system. Method: The method was developed by a multidisciplinary working group. It is based on a site visit guided by a tool called the Technical Observation Log (COT). It allows for the systematic recording of information necessary to identify and characterize exposed workstations, including the processes used, workshop ventilation, protective equipment, the characteristics of NOAA at the workstation’s entry and exit points, and the conditions of their handling, workstation operation, and maintenance. The method was tested in ten companies. Following each visit, a mission report listing workstations potentially exposed to NOACs was sent to the visited company. A copy of the digitized COT data was attached to the report for verification and validation. Results: all mission reports were validated. Of the 53 workstations observed, 30 (57%) were classified as potentially exposing workers to NOAAs, particularly those involved in the synthesis, sampling, transfer, and functionalization of NOAAs. The proportion of workstations potentially exposing workers to NOAAs was 54% in private companies and 60% in public companies. Numerous parameters appear to be decisive in classifying a workstation, particularly the fineness and moisture content of the NOAAs. Knowledge of these parameters can also be used in applying the graded risk management approach and, consequently, be useful to the company. Conclusion: This simple, non-instrumental method (requiring no sampling or aerosol measurement), designed for epidemiologists, could be useful to all stakeholders in occupational health and safety involved in managing risks associated with nanomaterials.