According to the definition in the German technical rules for workplaces, ASR A2.1, workplaces and access routes that are at least 2 m away from a falling edge are not classified as being located in a fall danger zone. The other way around, this means that all areas that are closer than 2 m to the falling edge are located in a fall danger zone.
Individuals are only allowed to work within 2 m of a falling edge, if they are accordingly secured against falls. When thinking about how to secure these individuals, collective protective measures, such as guard rails and safety nets, are to be given preference over individual personal fall protection measures.
If a collective protection solution is not technically feasible, personal fall protection equipment (PPE) has to be used. Trained individuals can secure themselves using this equipment by hooking up to pre-installed and approved anchorage devices. This equipment includes a safety harness and a suitable means of attachment (e.g. a connector).
If there are no permanently-installed anchorage devices, rails or lifeline systems on the building structure, you might want to try using a mobile anchorage device.