Lone worker
A lone worker is anyone who performs their job without close or direct supervision, or out of sight and earshot of colleagues who could help in an emergency.
Lone work is broader than it sounds. It includes the obvious cases - a community nurse on home visits, a security guard on night patrol, a utilities technician at a remote site - and the less obvious ones: a retail worker closing a store alone, a receptionist after colleagues leave, a support worker alone in a client's home with the client present. The client being there does not make it supervised work; it is often the source of the risk.
The law in Australia, New Zealand and the UK does not ban lone work, but it holds employers to the same duty of care as for any other worker - which in practice demands more, because the usual safety net of nearby colleagues is absent. Risk assessments must specifically consider what happens if a lone worker is threatened, injured, or incapacitated with nobody there to notice.
The monitoring data shows why the gap matters: alarms raised after hours - when supervision is thinnest - are roughly twice as likely to be confirmed emergencies as alarms raised during the working day.