Why are there separate electric (E) and magnetic (H) MPE limits at frequencies below 300 MHz?

At frequencies below 300 MHz, wavelengths are relatively long, meaning the 'near field' of an antenna can extend a significant distance. In the near field, the electric (E) and magnetic (H) fields are not neatly coupled together like they are in a far-field plane wave. Because the E and H fields behave independently close to the antenna, and because ground reflections and scattering can create distinct hot spots for each field at different locations, they must be measured separately. The human body absorbs energy from both fields, so evaluating both independently is critical to ensuring an area is truly safe from RF hazards.