Exposure triggered health questionnaires by linking real-time RF-EMF measurements to a smartphone application

Abstract

Introduction Studying acute effects of radiofrequency electromagnetic fields (RF-EMF) in observational studies often involves retrospective collection of questionnaires with hours or days between exposure and experienced health effects, making it difficult to link symptoms to exposure events. We developed a smartphone app prompting health status related questions, when triggered by pre-set exposure events detected in real-time by an exposimeter. A feasibility study was performed. Methods Participants were asked to install the app on their smartphone and to carry a RF exposimeter for 48 hours. Data was sent via Bluetooth to the application every 8 seconds. A questionnaire was triggered if: 1) a tenfold relative exposure increase compared to the average of the past half hour occurred, 2) exposure exceeded 10 mW/m², 3) a phone call was registered, and 4) no questionnaire was triggered for the past 1.5 hours (control). The questionnaire comprised 10 questions concerning current wellbeing. Unanswered questionnaires disappeared after 10 minutes. Minimum time between questionnaires was 45 minutes. Participants were asked to fill in an evaluation questionnaire. We evaluated the percentage of completed questionnaires, trigger reasons, and whether participants perceived influence on daily activities. Results We obtained complete data of 33 out of 46 participants (average age 32 (18-59)). Data from 13 participants were unusable due to technical failures. Participants received on average 9 (IQR 9-11) questionnaires per day of which 75% (IQR 69%-79%) were filled in. Main trigger reason was relative increase (61%) followed by control conditions (28%). 27 participants reported minimal influence, 6 reported some influence on daily activities. Conclusions Asking real-time exposure triggered questions using a smartphone app is feasible and has the potential to be applied to other types of exposure. Response rates were about 75% having limited influence on daily activities of participants.