  Pennes' differential equation for bioheat transfer and the heat transfer
equation are solved for the temperature distribution in a living tissue with
spherical inclusions, irradiated by microwave power. It is shown that relative
temperature excess in a small inclusion in the tissue in some cases is
inversely proportional to its radius and does not depend on the applied power.
In pulsing RF fields the effect is amplified proportionally to the ratio of the
pulse period to the pulse duration. The local temperature rise significantly
outpaces the averaged one and therefore the Watt to Weight SAR limits may be
insufficient to estimate the safety of RF radiation and the conventional
division of the biological effects of electromagnetic fields on the thermal and
non-thermal needs to be revised.
