Many exposure limits have different limits for two groups, broadly corresponding to "public" and "occupational". But the exact definitions vary:
from the glossary:
"Occupational exposure. All exposure to EMF experienced by individuals in the course of performing their work."
"Public exposure. All exposure to EMF experienced by members of the general public, excluding occupational exposure and exposure during medical procedures."
"controlled environment: An area that is accessible to those who are aware of the potential for exposure as a concomitant of employment, to individuals cognizant of exposure and potential adverse effects, or where exposure is the incidental result of passage through areas posted with warnings, or where the environment is not accessible to the general public and those individuals having access are aware of the potential for adverse effects."
"general public: All individuals who may experience exposure, except those in controlled environments."
NRPB use the terms "occupational exposure situation" and "general public exposure situation" but do not define them.
"Occupational exposure in these guidelines refers to adults exposed to time-varying electric, and magnetic fields from 1 Hz to 10 MHz at their workplaces, generally under known conditions, and as a result of performing their regular or assigned job activities."
Justification for different limits
These organisations give different explanations for the different exposure limits for the different groups:
"The occupationally exposed population consists of adults who are generally exposed under known conditions and are trained to be aware of potential risk and to take appropriate precautions. By contrast, the general public comprises individuals of all ages and of varying health status, and may include particularly susceptible groups or individuals. In many cases, members of the public are unaware of their exposure to EMF. Moreover, individual members of the public cannot reasonably be expected to take precautions to minimize or avoid exposure. It is these considerations that underlie the adoption of more stringent exposure restrictions for the public than for the occupationally exposed population."
"Protection is to be afforded to individuals in the general population and to groups in controlled environments. It is assumed that for the controlled environment, education and various mitigating measures can be taken to reduce the probability of adverse reactions of exposed individuals, although the exposure limits should protect against adverse effects for almost all people, with the possible exception of spark discharges within electric fields in the controlled environment. However, if adverse effects under some circumstances are anticipated, they can be mitigated with precautionary measures that are appropriate to the anticipated exposure situation. Examples of such measures include protective gloves or clothing, awareness programs designed to alert personnel to the possibility of effects, or specific work practices that lessen the frequency or intensity of exposure. For the general public accessibility is unconstrained and may include individuals uninformed of the potential for exposure or of possible adverse effects. Such exposure may occur in living quarters, areas open to the general public, workplaces where individuals do not anticipate exposure, or workplaces where workers are not aware of exposure conditions or prevention and mitigation procedures."
"It is noted that exposure in occupational situations will generally be to healthy adults working under controlled conditions. These conditions include the opportunity to apply engineering and administrative measures and, where necessary and practical, provide personal protection. It is also noted that the general public includes people of all ages and widely varying health status and exposure is likely to occur under uncontrolled conditions."
"Occupational exposure in these guidelines refers to adults exposed to time-varying electric, and magnetic fields from 1 Hz to 10 MHz at their workplaces, generally under known conditions, and as a result of performing their regular or assigned job activities. By contrast, the term general population refers to individuals of all ages and of varying health status which might increase the variability of the individual susceptibilities. In many cases, members of the public are unaware of their exposure to EMF. These considerations underlie the adoption of more stringent exposure restrictions for the public than for workers while they are occupationally exposed."