Seafarers' work exposure to tonal noise components

The requirement of better workers' psychophysical health and the wish to guarantee a correct comfort also during work activities, induce to consider the presence of significant pure tones also for the working spaces. However, the current European legislation regarding professional exposure to the noise of the workers, and namely the EU Directive 2003/10/CE, does not take into consideration the possible presence of pure tones in working noise. The same lack can be noticed in the standard ISO 1999:2013. As regards seafarers, the reference codes are the International Maritime Organization (IMO) Resolution A.468(XII) for ships built before 1 July 2014, and Resolution MSC.337(91) for newer ships. While tonal components are mentioned in the first one, stating that, if these are "obvious", the ISO noise rating (NR) number should be also determined, in the latter and most recent IMO Resolution no reference to tonal components is present. Tonal components cause annoyance and, at the same time, they induce hearing damage and can alter the behavior of workers, with a potential risk for the safety of ships. In this study, noise measurements taken onboard different ships are analyzed in order to determine seafarers' work exposure to tonal components. The survey includes different work spaces. To assess the presence of tonal components in crew's work environments the methodology of environmental noise analysis, defined in the Annex B of Italian Decree D.M. 16/3/98, has been used, making reference to ISO 226:2003 for determining normal equal-loudness level contours. The method used in order to evaluate tonal components is well established for the environmental noise annoyance and therefore it can be operatively extended to the workplace noise exposure. Results show that the presence of tonal disturbing components is not sporadic and therefore worthy of further analysis and regulation.