The further away you are from an EMF/EMR emitting device the lower your exposure.
Ideally cell phone antenna base stations should be at least 500 m away from your home/school/place of work. TV and radio broadcast antennas should be at least 2 km away. These values are based on cancer research, which shows an association between chronic (constant) RF exposure and the risk of developing or dying from various types of cancers with leukaemia being the most common. However, some highly sensitive individuals may find these levels to be excessive.
Similarly, the further away you are from smart meters, cell phones an other wireless devices the lower your exposure. Indeed cell phone manufacturers provide a clause in their manuals for you to keep at minimum distance of at least ~2cm between a cell phone and your body. The same applies for lap top computers in Wi-Fi mode although the recommended distance is closer to 20 cm.
When it comes to power lines, the more current flowing along the wires the higher the magnetic field. Consequently power lines with multiple wires or thicker wires generally emit a higher magnetic field. Also, field strength varies with time of day. When more power is required the magnetic field is higher. Field strength of approximately 3 mG has been linked to childhood cancers and slightly higher fields have been link to various adult cancers in occupational settings. Once again a distance of approximately 50 m should be sufficient to ensure that the magnetic field is less than 3 mG from either a distribution or a transmission power line.
Power lines also emit an electric field and this is based on the line voltage set by the electric utility. Electric fields are also biologically active although they do not penetrate buildings and hence are less of a concern inside a dwelling when the source is external to the building.