Staff noise exposure during neonatal transportation

Abstract

Introduction: Interhospital patient transfers are undertaken internationally by dedicated teams of specifically trained personnel performing many transfers per shift. The West of Scotland Neonatal Transport Service undertakes 700 transfers per annum using ambulances, helicopters and aeroplanes. There has been concern that such transfers were significantly noisy, and recent European legislative changes have decreased the permitted sound level that staff may be exposed to. This study aimed to assess the sound level staff were exposed to during neonatal transport. Methods: Personal sound level meters (CR:110A) were worn by staff throughout their shift. Thirty staff days were measured to assess the daily difference in workload. Staff recorded times, direction, mode of transport, location in the ambulance, whether the baby was on board and siren usage. Data were analysed for the whole shift, including daily personal noise level ‘Lex,8h’ dB(A) and maximum sound pressure level ‘Peak’ dB(C), with individual journeys analysed including equivalent continuous sound pressure level ‘Leq’ dB(A) and Peak dB(C). These data were compared with legislative standards (The Control of Noise at Work Regulations UK 2005). Results: Thirty-one staff shifts were measured. One shift excluded for Peak and another for LEX due to collection error, leaving 29 shifts for LEX and Peak. A total of 112 journeys were performed (median three per day); 20% of shifts exceeded the LEX lower exposure action level, and 3% exceeded the LEX upper exposure action level. Mean LEX was 76.1 dB. A total of 73% of shifts exceeded Peak lower exposure action levels, 47% of shifts exceeded peak upper exposure action level, and 23% shifts exceeded Peak exposure limit value. The Leq values of individual journeys ranged from 70.6 to 86.3 dB (median 78.9 dB). Journeys in the back of the ambulance averaged 2.7 dB louder, and journeys with the baby on board averaged 2.5 dB louder. Journeys involving intermittent siren use averaged 3.2 dB louder. Conclusions: The majority of shifts exceed legal limits for Peak sound level, but LEX was only rarely exceeded. This prompted an ambulance review, hearing protection provision and an annual surveillance of hearing. Our transport network has been alerted to this risk, and we believe that these data evidence a risk for patient transport teams worldwide.