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The Impact of Different Permissible Exposure Limits on Hearing Threshold Levels Beyond 25 dBA

BACKGROUND: Development of noise-induced hearing loss is reliant on a few factors such as frequency, intensity, and duration of noise exposure. The occurrence of this occupational malady has doubled from 120 million to 250 million in a decade. Countries such as Malaysia, India, and the US have adopt...

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Autores principales: Sayapathi, Balachandar S, Su, Anselm Ting, Koh, David
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Kowsar 2014
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4329756/
https://www.ncbi.nlm.nih.gov/pubmed/25763196
http://dx.doi.org/10.5812/ircmj.15520
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author Sayapathi, Balachandar S
Su, Anselm Ting
Koh, David
author_facet Sayapathi, Balachandar S
Su, Anselm Ting
Koh, David
author_sort Sayapathi, Balachandar S
collection PubMed
description BACKGROUND: Development of noise-induced hearing loss is reliant on a few factors such as frequency, intensity, and duration of noise exposure. The occurrence of this occupational malady has doubled from 120 million to 250 million in a decade. Countries such as Malaysia, India, and the US have adopted 90 dBA as the permissible exposure limit. According to the US Occupational Safety and Health Administration (OSHA), the exposure limit for noise is 90 dBA, while that of the US National Institute of Occupational Safety and Health (NIOSH) is 85 dBA for 8 hours of noise exposure. OBJECTIVES: This study aimed to assess the development of hearing threshold levels beyond 25 dBA on adoption of 85 dBA as the permissible exposure limit compared to 90 dBA. PATIENTS AND METHODS: This is an intervention study done on two automobile factories. There were 203 employees exposed to noise levels beyond the action level. Hearing protection devices were distributed to reduce noise levels to a level between the permissible exposure limit and action level. The permissible exposure limits were 90 and 85 dBA in factories 1 and 2, respectively, while the action levels were 85 and 80 dBA, respectively. The hearing threshold levels of participants were measured at baseline and at first month of postshift exposure of noise. The outcome was measured by a manual audiometer. McNemar and chi-square tests were used in the statistical analysis. RESULTS: We found that hearing threshold levels of more than 25 dBA has changed significantly from pre-intervention to post-intervention among participants from both factories (3000 Hz for the right ear and 2000 Hz for the left ear). There was a statistically significant association between participants at 3000 Hz on the right ear at ‘deteriorated’ level ( χ² (1) = 4.08, φ = - 0.142, P = 0.043), whereas there was worsening of hearing threshold beyond 25 dBA among those embraced 90 dBA. CONCLUSIONS: The adoption of 85 dBA as the permissible exposure limit has preserved hearing threshold level among participants at 3000 Hz compared to those who embraced 90 dBA.
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spelling pubmed-43297562015-03-11 The Impact of Different Permissible Exposure Limits on Hearing Threshold Levels Beyond 25 dBA Sayapathi, Balachandar S Su, Anselm Ting Koh, David Iran Red Crescent Med J Research Article BACKGROUND: Development of noise-induced hearing loss is reliant on a few factors such as frequency, intensity, and duration of noise exposure. The occurrence of this occupational malady has doubled from 120 million to 250 million in a decade. Countries such as Malaysia, India, and the US have adopted 90 dBA as the permissible exposure limit. According to the US Occupational Safety and Health Administration (OSHA), the exposure limit for noise is 90 dBA, while that of the US National Institute of Occupational Safety and Health (NIOSH) is 85 dBA for 8 hours of noise exposure. OBJECTIVES: This study aimed to assess the development of hearing threshold levels beyond 25 dBA on adoption of 85 dBA as the permissible exposure limit compared to 90 dBA. PATIENTS AND METHODS: This is an intervention study done on two automobile factories. There were 203 employees exposed to noise levels beyond the action level. Hearing protection devices were distributed to reduce noise levels to a level between the permissible exposure limit and action level. The permissible exposure limits were 90 and 85 dBA in factories 1 and 2, respectively, while the action levels were 85 and 80 dBA, respectively. The hearing threshold levels of participants were measured at baseline and at first month of postshift exposure of noise. The outcome was measured by a manual audiometer. McNemar and chi-square tests were used in the statistical analysis. RESULTS: We found that hearing threshold levels of more than 25 dBA has changed significantly from pre-intervention to post-intervention among participants from both factories (3000 Hz for the right ear and 2000 Hz for the left ear). There was a statistically significant association between participants at 3000 Hz on the right ear at ‘deteriorated’ level ( χ² (1) = 4.08, φ = - 0.142, P = 0.043), whereas there was worsening of hearing threshold beyond 25 dBA among those embraced 90 dBA. CONCLUSIONS: The adoption of 85 dBA as the permissible exposure limit has preserved hearing threshold level among participants at 3000 Hz compared to those who embraced 90 dBA. Kowsar 2014-10-05 /pmc/articles/PMC4329756/ /pubmed/25763196 http://dx.doi.org/10.5812/ircmj.15520 Text en Copyright © 2014, Iranian Red Crescent Medical Journal; Published by Kowsar. http://creativecommons.org/licenses/by-nc/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/) which permits copy and redistribute the material just in noncommercial usages, provided the original work is properly cited.
spellingShingle Research Article
Sayapathi, Balachandar S
Su, Anselm Ting
Koh, David
The Impact of Different Permissible Exposure Limits on Hearing Threshold Levels Beyond 25 dBA
title The Impact of Different Permissible Exposure Limits on Hearing Threshold Levels Beyond 25 dBA
title_full The Impact of Different Permissible Exposure Limits on Hearing Threshold Levels Beyond 25 dBA
title_fullStr The Impact of Different Permissible Exposure Limits on Hearing Threshold Levels Beyond 25 dBA
title_full_unstemmed The Impact of Different Permissible Exposure Limits on Hearing Threshold Levels Beyond 25 dBA
title_short The Impact of Different Permissible Exposure Limits on Hearing Threshold Levels Beyond 25 dBA
title_sort impact of different permissible exposure limits on hearing threshold levels beyond 25 dba
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4329756/
https://www.ncbi.nlm.nih.gov/pubmed/25763196
http://dx.doi.org/10.5812/ircmj.15520
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