Smart meters have a computer and some other electronic equipment in them that, unless carefully shielded, radiate miniscule amounts of non-ionising electro-magnetic energy at various frequencies. Some types communicate by sending low-power RF signals along the electricity supply cables. Many can be read electronically with hand-held devices, again using low-power RF signals. Mobile phones give off much more RF energy than smart meters yet people willingly hold them close to their heads.
NSW readers should note that moving the meters (as distinct from updating them) would be a change to the infrastructure and would require passing as a special resolution at a general meeting with not more than one-quarter by value of the votes cast against it.