Noise is one of the most common physical factors in the work environment, which exists with different intensities in almost all industries. In general, no industry can be found that is safe in terms of noise pollution. When the sound level exceeds the permissible limit, it can create harmful effects on the functioning of other parts of the body, including blood circulation, nervous system, and work efficiency, in addition to the hearing system. In addition to sound level, other factors that can intensify the effect of sound include age, gender, eye and skin color, sound frequency range, time duration of sound and duration of contact with sound.The average hearing threshold in people over 30 years old is more than people who are under 30 years old. Noise as a physical stress can also increase blood pressure, heart rate and oxygen consumption. Stay with Amin Business Group about this...
There are no accurate statistics on the level of exposure to noise in Iran, but it can be imagined that the dimensions of this problem are significant in Iran as well. In 2018, all the workers of a tile factory located in Yazd, who were exposed to noise greater than or equal to 85 decibels, were examined.Pure tone audiometry test was done for 372 workers. Exclusion criteria include: history of diabetes, hyperlipidemia, hypothyroidism, hyperthyroidism, kidney disease, ear diseases (otitis media and tympanic membrane rupture in otoscopic examination), working in a noisy environment other than a factory, meningitis, exposure to noise It was a sudden explosion and consumption of ototoxic drugs. In this test, people's hearing threshold was measured and recorded based on air conduction in each ear at frequencies of 500, 1000, 2000, 3000, 4000, 6000 and 8000 Hz. Audiograms were considered normal if none of the hearing thresholds were less than 20 dB. 
Out of a total of 1000 workers working in this factory, 381 of them faced noise of more than 85 decibels.
Based on the exclusion criteria, 9 people were excluded from the study. It should be mentioned that the most noisy parts of the factory include the body preparation hall with a sound pressure level of 91 decibels and a press hall with a sound pressure level of 86 decibels.The average age and work experience of the subjects were 2.32 ± 9.6 and 5.9 ± 4.6 years, respectively. 4.91% of the examined people had normal hearing and 6.8% of them had different degrees of hearing loss, so that 7.6% of people with mild hearing loss (hearing threshold between 21-40 dB), 6.1% had Moderate hearing loss (hearing threshold between 41-60 decibels) and 0.3% of people had severe hearing loss (hearing threshold between 61-80 decibels), and there was no case of very severe hearing loss in people.
In order to investigate the relationship between the hearing threshold and the age of the workers and their work experience, the studied subjects were divided into two age groups: less than or equal to 30 years and more than 30 years, and also in terms of work experience into two groups: work experience less than or equal to 10 years and They were divided for more than 10 years. The results of this study showed that with increasing age of workers, the average hearing threshold also increases (P<0.001). Work experience is also one of the effective factors in the reduction of occupational hearing, so that in this research, 4% of the workers whose work experience was less than 10 years had abnormal hearing, while in the workers whose work experience was more than 10 years, % 19 had abnormal hearing, and this difference is also statistically significant (P<0.001). Table: Hearing status of tile factory workers Hearing status | right ear (%) | left ear (%) | both ears (%) |
normal hearing | 3/94 | 6/92 | 4/91 |
Mild hearing loss | 3/4 | 3/4 | 7/6 |
Moderate hearing loss | 9/0 | 6/1 | 6/1 |
Severe hearing loss | 5/0 | 6/1 | 3/0 |
It seems that noise-induced hearing loss is a common disease in Iran due to the growth of industries and technological progress in the last few decades, and there is not enough information about the level of occupational exposure to noise and its relationship with hearing loss. It is necessary to conduct comprehensive studies in various fields of NIHL at the national level.
Amin Commercial Group is an importer and supplier of tile and ceramic raw materials and industrial parts 