This exposure assessment study analyzed smartphone-logged 4G LTE RSSI and GPS data from adults in France to identify determinants of downlink signal strength. RSSI varied with geospatial factors (distance to antennas, antenna density, urbanicity) and time of day, and was also influenced by technical smartphone parameters. The study reports an estimated electric field strength derived from RSSI, but notes high uncertainty in this conversion.

This protocol and pilot study evaluated whether smartphone signal strength indicators can be converted into RF-EMF exposure estimates using derived formulas and regression models. The study reports a positive log-linear association between LTE RSSI and far-field (base station) exposure aggregated by location, while handset-related exposure at the ear and chest during data transmission showed negative log-linear trends with improving signal quality. The authors conclude the ETAIN 5G-Scientist app may support large-scale RF-EMF exposure assessment, but emphasize the need for more data to improve accuracy and address uncertainties in individual measurements.