Abstract Exposure to low-frequency electromagnetic fields (EMF) has become an issue considering a number of high-power low-frequency EMF sources installed in residential environment. Therefore, the EMF monitoring and appropriate exposure assessment are highly important regarding the safety, since residents can spend considerable time in the vicinity of such high-power objects. This short paper brings the case study related to the broadband continuous monitoring of the low-frequency magnetic field in the vicinity of the outdoor power substation, as a particularly important and interesting EMF source. Moreover, the exposure assessment of the general population, performed by a newly proposed adaptive boundary exposure approach, is presented. This approach assesses the upper and lower daily exposure boundaries, offering the range where real exposure is positioned. The reduction of difference between boundaries can be attained by frequency spectrum analysis, while in this case study the initial boundary difference was reduced from 99.6% to 33.3%.