Part of a crew on a Norwegian naval ship was exposed to the radar waves for approximately 7 min from an American destroyer during an incident at sea in August 2012. Information about the exposure was not given by the navy. This is a description of what happened with the crew on board after this event. 14 persons had been on the ship bridge or outside on the deck during the exposure and the rest of the crew had been inside the ship. 27 persons were examined at a hospital 6-8 months after the event, as they had developeda large number of symptoms from different organ systems. They were very worried about all types of possible adverse health effects due to the incident. All were examined by an occupational physician and anophthalmologist, by an interview, clinical examinations and blood tests at the hospital. The interview of the personnel revealed that they had not experienced any major heating during the episode. Their symptoms developed days or weeks after the radar exposure. They had no objective signs of adverse health effects at the examination related to the incident. Long-term health effect from the exposure is highly unlikely. The development of different symptoms after the incident was probably due to the fear of possible health consequences. Better routines for such incidents at sea should be developed to avoid this type of anxiety.
Prior studies have indicated a high prevalence of noise-induced hearing loss (NIHL) among Navy personnel; however, it is not clear whether this is caused by work on board. The present study aimed to assess the prevalence of hearing loss among Navy personnel in the Royal Norwegian Navy (RNoN), and to investigate whether there is an association between work on board RNoN vessels and occurrence of hearing loss.
Navy personnel currently working on board RNoN vessels were recruited to complete a questionnaire on noise exposure and health followed by pure tone audiometry. Hearing loss was defined as hearing threshold levels =25 dB in either ear at the frequencies 3,000, 4,000 or 6,000 Hz. Hearing thresholds were adjusted for age and gender using ISO 7029.
The prevalence of hearing loss among Navy personnel was 31.4 %. The work exposure variables: years of work in the Navy, years on vessel(s) in the Navy and years of sailing in the Navy were associated with reduced hearing after adjusting for age, gender and otitis as an adult. Among the work exposure variables, years of sailing in the Navy was the strongest predictor of reduced hearing, and significantly reduced hearing was found at the frequencies 1,000, 3,000 and 4,000 Hz.
Our results indicate that time spent on board vessels in the RNoN is a predictor of reduced hearing.
Despite awareness of noise aboard vessels at sea, few studies have reported measured noise levels aboard ships. This study aimed to describe the noise levels aboard vessels in the Royal Norwegian Navy (RNoN), and to assess the noise exposure of personnel aboard RNoN vessels. In 2012/2013 noise measurements were conducted aboard 14 RNoN vessels from four different vessel classes (frigates, coastal corvettes, mine vessels, and coast guard vessels) which were included in this study. Mean and median A-weighted noise levels (L p,A) in decibel (dB(A)) were calculated for different locations in each vessel class. The noise exposure of RNoN personnel was assessed by dosimeter measurements, and with a task-based (TB) strategy. The TB strategy used means of area measured noise levels in locations and the personnel's mean reported time spent in the respective locations to estimate the exposure. Area measurements of noise during sailing with typical operating modes, showed that for all vessel classes the noise levels were high in engine rooms with median L p,A ranging from 86.4 to 105.3 dB(A). In all the other locations the vessel class with the highest noise levels (coastal corvettes) had a median L p,A ranging from 71.7 to 95.0 dB(A), while the vessel class with the lowest noise levels (coast guard vessels) had a median L p,A ranging from 41.5 to 57.8 dB(A). For all vessel classes the engineers and electricians had amongst the highest 24-hour noise exposure (L p,A,24h), both before and after adjusting for estimated use of hearing protective devices (L p,A,24h > 67.3 dB(A)). The vessel class with the highest personnel exposure levels (coastal corvettes) had L p,A,24h ranging from 76.6 to 79.3 dB(A). The vessel class with the lowest personnel exposure levels (coast guard vessels) had an L p,A,24h ranging from 47.4 to 67.3 dB(A). In general, the dosimeter measurements gave higher exposure levels than those estimated with the TB strategy. All vessel classes, except the coast guard vessels, had noise levels exceeding the RNoN standard's recommended maximum noise levels. The area measured noise levels and the personnel's exposure estimates indicate that navy personnel aboard RNoN vessels are at risk of acquiring adverse health effects from exposure to noise, and that a program to reduce the noise levels should be implemented.