Hindawi Publishing Corporation Te Scientifc World Journal Volume 2013, Article ID 923731, 7 pages http://dx.doi.org/10.1155/2013/923731 Research Article Effect of Workplace Noise on Hearing Ability in Tile and Ceramic Industry Workers in Iran: A 2-Year Follow-Up Study Mehrdad Mostaghaci, 1 Seyyed Jalil Mirmohammadi, 1 Amir Houshang Mehrparvar, 1 Maryam Bahaloo, 2 Abolfazl Mollasadeghi, 1 and Mohammad Hossein Davari 1 1 Department of Occupational Medicine, School of Medicine, Shahid Sadoughi University of Medical Sciences, Shahid Rahnemoun Hospital, Farrokhi Avenue, Yazd 89138-14389, Iran 2 Industrial Disease Research Center, Shahid Sadoughi University of Medical Sciences, Shahid Rahnemoun Hospital, Farrokhi Avenue, Yazd 89138-14389, Iran Correspondence should be addressed to Maryam Bahaloo; drbahaloo@gmail.com Received 30 August 2013; Accepted 30 September 2013 Academic Editors: R. Pohjanvirta and J.-M. Sabatier Copyright © 2013 Mehrdad Mostaghaci et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Introduction. Noise as a common physical hazard may lead to noise-induced hearing loss, an irreversible but preventable disorder. Annual audiometric evaluations help detect changes in hearing status before clinically signifcant hearing loss develops. Tis study was designed to track hearing threshold changes during 2-year follow-up among tile and ceramic workers. Methods. Tis follow- up study was conducted on 555 workers (totally 1110 ears). Subjects were divided into four groups according to the level of noise exposure. Hearing threshold in conventional audiometric frequencies was measured and standard threshold shif was calculated for each ear. Results. Hearing threshold was increased during 2 years of follow-up. Increased hearing threshold was most frequently observed at 4000, 6000, and 3000 Hz. Standard threshold shif was observed in 13 (2.34%), 49 (8.83%), 22 (3.96%), and 63 (11.35%) subjects in the frst and second years of follow-up in the right and lef ears, respectively. Conclusions. Tis study has documented a high incidence of noise-induced hearing loss in tile and ceramic workers that would put stress on the importance of using hearing protection devices. 1. Introduction Noise is the most common physical hazard in the industrial workplaces. A report from the European Union mentions that about 28% of workers are exposed to noise level approxi- mately between 85 and 90 dBA [1]. Te most common health problem due to exposure to noise is noise-induced hearing loss (NIHL), an irreversible but preventable disorder [2]. NIHL is the second most common form of acquired hearing loss, afer presbycusis [3, 4], and is a major concern for workers’ health in diferent countries [4–6]. In the industrial settings, when noise exceeds permissible levels, hearing conservation program should be started, which contains hearing evaluation and some other activities. In 1996 National Institute of Occupational Safety and Health (NIOSH) reported that about 30 million workers in USA are exposed to loud noise which can lead to hearing loss [7]. It is estimated that 10 million workers sufer from NIHL in USA [8]. NIHL is typically a bilateral and symmetric hearing loss with a notch of the audiogram at 3, 4, or 6 kHz and a recovery at 8 kHz as the frst sign [4]. Tis hearing impairment may be aggravated if exposure to noise is continued [9, 10]. Prevention of deafness and hearing impairment (PDH), a WHO program, is especially planned for developing coun- tries due to lack of accurate population-based studies about the prevalence and causes of deafness and hearing loss [11– 13]. Occupational Safety and Health Administration (OSHA) requires that all workers exposed to noise more than 85 dBA be screened for NIHL annually [14]. Standard threshold shif (STS) is defned as a 10 dB or more change in average hearing threshold at 2000, 3000, and