10.6.2 Evaluating Exposure
The next step is to determine exposure during actual and reasonably foreseeable maximum operating conditions.
Exposure may be evaluated using one or more of the following:
- current site measurements or validated previous measurements;
- direct RF field or power-density measurements;
- computational modeling;
- manufacturer or operator technical information;
- analytical calculations; or
- validated assessments of genuinely comparable installations.
The method must suit the source, field region, frequency range, exposure metric, and spatial variation. Far-field plane-wave conditions may support relatively simple calculations or measurements. Reactive near-field, radiating near-field, large-aperture, highly non-uniform, or multiple-source environments may require separate electric- and magnetic-field measurements, spatial averaging, frequency-weighted summation, or computational modeling. The uncertainty and validation controls described in Chapter 8 and the applicable assessment standards must be included.
10.6.3 Comparing Exposure With Applicable Limits
Measured or calculated exposure, including the effect of assessment uncertainty, should be compared with the relevant occupational or general public reference levels and, where necessary, the corresponding basic restrictions.
Compliance is normally demonstrated when the applicable reference levels and simultaneous-source summation requirements are satisfied under the relevant spatial- and time-averaging conditions. If a reference level is exceeded, compliance may still be demonstrated by a more detailed assessment against the corresponding basic restriction.
Exceeding a reference level is therefore not, by itself, proof that a basic restriction has been exceeded. It is a trigger for further assessment or additional controls. Access should not be permitted on the assumption of compliance while the more detailed assessment remains unresolved.