Does the signal affect things like pacemakers?
Laboratory and clinical tests have found that digital wireless phones, which operate in a similar manner to TETRA, might interfere under certain conditions with some pacemakers and hearing aids. Users can take steps to minimise or prevent interference, such as keeping an operating handset a minimum of six inches (15 cm) from an implanted pacemaker or adopting other measures to accommodate the use of hearing aids. Users should always follow the advice provided by the manufacturers of medical equipment.