Journal of Health and Safety at Work

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Introduction: According to previous researches, working at the airport is one of the most vociferous jobs in the world. Airport workers are at risk of noise induced hearing loss. The present study was done to evaluate the Sound Pressure Level (SPL) in the closest aprons to Ground Safety department at Mehrabad airport and to investigate the effect of airport noise on the employees of this department.

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Material and Methods: Evaluation of SPL in the given aprons was done using sound meter and sound analyzer. Measurement stations at specific intervals to the sound source were identified inside and outside of the participants 'workplace and SPL was measured at night and day. The mean estimated values were compared with those presented by Ministry of Health. The annual participants' audiometry information was extracted from medical records. Then a self-administered questionnaire was distributed among the study sample in order to measure quality of noise exposure. The questionnaire was developed based on three general criteria including the knowledge toward the noise pollution, job satisfaction, and the exposure to the noise source and the purpose of this questionnaire was to find the relationship (correlation) between these parameters among the study population.

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Result: The measured equivalent for 8 hours noise exposure was obtained 94 dB(A) and no relation was observed between octave band sound of aircraft and recorded audiometry. Analysis of the questionnaire showed that people with more knowledge about noise pollution used more hearing protective equipment. Subsequently, by using more hearing protection equipment the level of hearing loss was reduced significantly (P<0.05). There was a significant and negative correlation between noise exposure and job satisfaction, as well (P<0.05). Also there was a significant and negative correlation between using of ear muffs and catching Noise-Induced Hearing Loss (P<0.1). The percentage of noise-induced hearing loss was calculated 51.4% among study sample.

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Conclusion: The noise exposure of employees of Ground Safety working in Mehrabad airport was higher than the permissible limit which implies the necessity for use of earmuffs and implementation of noise reduction programs.

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Introduction: The use of hearing protective devices (HPDs) is the last way for noise control. It is important to know the information about the duration time using these devices to ensure protetion effectiveness. The aim of this study was to investigate the effect of increasing duration time of the using of the devices on hearing loss in tile industry workers with application of the BASNEF education model.  

Material and Method: Task Base Method (TBM) and ISO9612(2009) standard methods through a noise dosimeter device were used to exmine workers’ noise exposure level when they didn’t used of HPDs. Actual performance of HPDs was determined by using the NIOSH standard before and after training intervention and measuring time of use and protection device type. Data were analyzed using SPSSVv19 and conducting t-test and ANCOVA statistical tests.   

Result: Before training intervention, the actual noise level for case workers was 89.76 dBA. On the contrary, this value was 84.04 dBA for after intervention, with a significant difference with control group (P<0.0001) using ANCOVA analysis. In control group, the actual level of noise has not changed because this group has not received any training.

Conclusion: The results revealed that, based on BASNEF education model, duration time of using hearing protection devices is effective on increasing their function and performance.

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Introduction: Colored noises with acoustic and psychoacoustic characteristics have several biological effects on human or animal health. While studies on auditory effects focus on noise’s physical aspects, its psychoacoustic aspects can also result in health and safety risks. Therefore, this study aims to investigate frequency-based damages due to exposure to colored noise in an animal model.
Material and Methods: Twenty-four male Wistar rats were randomly divided into four groups (6 in each group). The groups included the control (no exposure) and three exposure groups (white, pink, and violet). The rats were exposed to 110 dB SPL for 4 hr/day for 14 consecutive days. Auditory brainstem responses (ABR) with click and tone-burst stimuli were recorded one day before (baseline), 7, and 14 days after exposure. Statistical analyses were conducted using ANOVA and repeated measures ANOVA.
Results: There was a statistically significant increase in ABR threshold values in exposure groups (p<0.05). Hearing threshold shifts in the white noise group showed a homogeneous pattern, violet noise showed an increasing pattern, and pink noise showed a decreasing pattern in low frequencies and a homogeneous pattern with increasing frequency. The highest shift in hearing threshold was observed in exposure groups from day 0 to 14. Additionally, the shift in hearing threshold in the second week was less than in the first one.
Conclusion: The current study observed that noise’s power spectral density affected hair cells’ damage severity. Accordingly, pink noise causes less damage to the cochlea compared to white and violet. Over time after noise exposure, cochlear pathogenesis gradually decreases and hair cell lesions become stable.