Evaluation of occupational noise exposure and general health of workers in industrial sites: A case study

Abstract

BACKGROUND:

Occupational noise exposure in workplaces is the most common detrimental factor that has the greatest impact on the health of people working there.

OBJECTIVE:

The aim of this study was to evaluate occupational noise exposure and its relation to the general health status in industrial workers in Sanandaj, Iran.

METHODS:

This cross-sectional study was conducted on the general health of 500 male workers in Sanandaj using the General Health Questionnaire (GHQ-28). Likewise, occupational noise exposure was measured based on sound pressure level (SPL) and dosimetry in the work and rest conditions of workers.

RESULTS:

The results showed poor general health status of workers, exceeded the daily working hours and also the standard range of sound. A significant correlation was found between general health and its dimensions with indicators of workplace sound pressure levels (P < 0.05). This means that with the increase in sound pressure level is worse general health status.

CONCLUSION:

It seems that the health of workers in these industries is an inappropriate process due to exposure to occupational noise exposure and poor conditions of the workplace. A high percentage of them will lose their health in case of non-implementation of prevention programs and health in the workplace in the future.

Keywords

General health occupational noise exposure industrial workers Sanandaj

1. Introduction

General health is regarded as one of the most prominent indicators that get the World Health Organization (WHO) stimulated to squeeze this item as a preventive item in health-treatment programs [1, 2]. While focusing on the throughput of a company, managers and high profile people should consider physical and mental conditions of staff [3]. There is a little doubt that any congregation is comprised of a number of physical, chemical, social, and mental factors, influencing all aspect of the life and determining how healthy the life is being in occupational sites for a long time is a factor getting researchers fostered to be drawing attention to it [4].

Occupational noise exposure is one of the most irretrievable factors that expose laborers to physical and mental risks. Studies have revealed that noise is the most excruciating factor, undergoing workers’ outputs. It is claimed that there are almost 600 million workers in the world who are encountering sonic pollution [5]. Demographic trends are reciting that there are about 2 million noise-exposed workers in Iran. Noise is defined as a combination of harsh sounds with various wavelengths and strengths; these components do not have vivid attributes and cause suffer the auditory system [6]. So that about 12 percent of hearing loss in the world is caused by occupational exposure to noise. In addition, it has physiological and psychological effects, causes occupational complications and increases the risk of accidents in the workplace [7].

Nervous sensitivity, harsh irritability, muscle spasm, both physical and spiritual boredom, stress and tension, dizziness, headache, anxiety, anger, body im-balance, bad temper, violence and distraction, the secretion of adrenaline hormone, sight weakness, weakness of sexual power, disorder of metabolism of digesting system, stomach ulcer, malnutrition, constipation, the intestine inflammation, awakening, loss of skin resistance, asthma, changes in electro-encephalography and blood vessels contraction, In-crease of blood pressure and arterial pressure, neonatal birth, educational failure, sharp decrease of job efficiency, are being mentioned as the most recognized side effects of exposure to occupational noise [8 –10].

Various studies have examined the general health status. For example, Mehrabian et al. reported a po-sitive and significant correlation between general health and job satisfaction [1]. Koohpaei et al. studied the general health status of workers among different workplaces and indicated that the general health score of the population was suitable in its entirety [11]. Furthermore, to investigate the effect of noise exposure on the general health in workplace, Rostami et al. showed that noise can be considered as a risk factor in the incidence of psychological disorders [12], and in study of Beheshti et al. there was a direct correlation between psychosomatic personality characteristics and noise annoyance and there was no relationship between demographic characteristics with noise annoyance [13].

The first evidence and primary studies recite that the prevailing noise level is far more than Recom-mended Exposure Limits (REL) according to the National Institute for Occupational Safety and Health (NIOSH) [14] in vocational workplaces in Sanandaj, Kurdistan province; consequently, there are numerous laborers whose hearing systems have been impaired. Rarely did all research (both nationally and locally) interrogate influence of noise on the general health; however, they partially deal with noise consequences on hearing problems. Consequently, there is no reliable database to be referred to. Is not this dilemma so critical to be concentrated on? The paramount importance of this topic, on the one hand, and not existing coherent and reliable studies, on the other hand, get us fueled to trigger the current research. To set out and suggest safety actions, related vocational sites have been monitored and the standard deviation of noise level has been evaluated. Simultaneously, holding array of preventive programs, such as Hearing Conservation Programs, were laid on the top of the agenda. Overall, the most important aim of the current study is dealing with the noisy condition in vocational places located at Sanandaj, Iran and taking a glance at the general health of those working there.

2. Methods

2.1. Subjects studied

This cross-sectional study was conducted on 72 active factories with a population of 5536 in Sanandaj, in 2017. To determine statistical society, the sample size was determined based on the following formula: $N = \frac{z^{2} P (1 - P)}{d^{2}}$

According to the instruction of WHO, we studied 10 percent of the society. Sampling was done as follows: $K = \frac{N}{n} = \frac{5536}{500} = 11$

Afterward, the number 7 was randomly chosen among 1 to 11 and with a distance of 11 people, other subjects were selected. Workers by sending an official letter, contact with industries managers, and referring researchers to factories were invited to participate in the study.

Inclusion criteria were: physical and mental health, non-smoking, no history of underlying disease (such as diabetes, cardiovascular and chronic kidney diseases) and use of specific drugs; while participants with any illness were excluded from the study. This study was approved by the ethics committee of the Kurdistan University of Medical Sciences.

2.2. Measuring tools

The study was conducted in two steps: firstly, the dta was acquired and analyzed; secondly, the general health of the exposed people was explored. First of all, those sites whose conditions do not meet the standard levels were recognized; then, some primary information such as the location of noise sources and labors in any operational unit and machines’ status were determined. Then, based on ISO 9612, sound measurement was performed to estimate the strength of occupational noise exposure. To measure how laborers were exposed to this issue, all kinds of stations ranging from resting and working were precisely monitored. Noise intensity was measured by a sound level meter model CASELLA-CEL.450. This sound level meter was calibrated by sound calibrator model CEL-1102. Since noise was continual and its variation per time was so low, network A was chosen as a measuring scale to evaluate occupational noise exposure across the studied factories. At each measuring station, the value of workplace noise was measured 3 times, and its average was recorded. The direction of the microphone was aligned with laborers’ heads (without their presence) according to standard ISO 9612 [15]. The height of the microphone was approximately 1.5 meter.

Since workers and operators do not stay in a constant location and continually commute in different parts of the site; thus, they do not receive a constant level of noise during 8-hour working time. To determine the dose of received noise by laborers, the dosimeter appliance TES-1345 was used. According to the Standard ISO 9612, after calibration by the calibrator CEL-282, dosimeter appliance was tied to the waist of workers and device microphone was installed on their collars at the 10 to 30 centimeter distance of the external auditory canal; then the dose of noise was measured.

2.3. General health assessment

A general health questionnaire (GHQ-28) was used to assess the health status of workers exposed to noise in industrial sites. GHQ was developed by Goldberg and Hiller in 1978 to identify psychiatric disorders in a society and its validity and reliability have been confirmed [16]. The questionnaire has been translated into several different languages, and its validity and reliability the Persian version have been confirmed in Iran [17, 18]. It consisted of 28 questions, examining the health conditions in 4 subscales. Firstly, measuring the physical symptoms that each individual has experienced during the last month (7 questions); secondly, stress and sleeping disturbance that subjects got involved with as: symptoms of insomnia, sense of being under pressure, anger, anxiety and frustration, and not being able to do works (7 questions); thirdly, ‘disruption of social function’ part that investigate capability of subjects in doing daily activities, satisfaction to doing tasks, sense of being helpful, power of making decision, and enjoying daily activities (7 questions); finally, this part sheds light on special symptoms of depression namely sense of worthless, disappointment, feeling the absurdity of life, death wish, and thoughts about suicide (7 questions). The answers were set in 5-grades based on a Likert-type scale (0 ‘never’ to 4 ‘always’). The sum of these scores shows the general health conditions of people: scores lower than 23 are considered as desirable and healthy condition and a score 23 and above indicates an unhealthy condition. Scoring on the subscales are follows: Individuals who received a score below 7 had possessed high-level health, 4–17 normal, and more than 14 critical status that must be tested.

Data were analyzed by using SPSS, Version 19, and Pearson correlation test and independent samples t-test were used. Significant level was considered less than 0.05.

3. Results

Five hundred laborers who were invited to participate in the study were, on average, 37.62±9.01 years and had approximately a 35-year experience. It should be noted that 85.5% (440 people) of them were married and 14.5% single (60 people). Table 1 showed the demographic information about statistical society. As can be seen, the laborers almost entirely have a normal height, weight, and BMI.

Table 1
Demographic findings and working hours of the participants

Variable Minimum Maximum Average Standard deviation

Age (years) 23 61 37.62 9.01

Height (centimeters) 157 196 174.13 9.24

Weight (kilograms) 50 108 77.2 10.26

BMI (kg/m²) 16.5 40 25.39 8.04

Working years 1 30 10.72 7.35

Working hours per day 7 14 9.03 1.63

Rest hours in a working day 0 2 0.98 0.24

Variable	Minimum	Maximum	Average	Standard deviation
Age (years)	23	61	37.62	9.01
Height (centimeters)	157	196	174.13	9.24
Weight (kilograms)	50	108	77.2	10.26
BMI (kg/m²)	16.5	40	25.39	8.04
Working years	1	30	10.72	7.35
Working hours per day	7	14	9.03	1.63
Rest hours in a working day	0	2	0.98	0.24

Results pointing to general health scores have been listed in Table 2. What was extracted from statistical analysis reveals that their general health condition is undesirable. Scores showed that ‘Insomnia’ had the highest score and ‘Depression’ the lowest. The paramount importance of family and social issues gets us pushed to investigate them in terms of marital status. Having demographically been examined the relationship of diverse dimensions of general health with family issues among the studied laborers, data depicted that general health of single people was far better than married ones; there was no significant correlation between general health and marital status, however (Table 3).

Table 2

General health scores and related subscales among the participants

Health scales	Minimum	Maximum	Average	Standard deviation
Physical health	1	15	7.85	2.85
Stress and insomnia	1	15	7.85	2.65
Social function	2	16	7.3	2.71
Depression	0	15	6.41	3.06
Overall score	15	56	29.13	8.74

Table 3

Comparison of the diverse dimension of general health and marital status among the participants

Variable	Married (n = 440)		Single (n = 60)		P-value
	Average	Standard deviation	Average	Standard deviation
Physical health	7.88	2.92	7.6	2.26	0.62
Stress and insomnia	7.85	2.52	7.82	2.35	0.94
Social function	7.2	2.73	6.6	2.55	0.27
Depression	6.5	3.11	5.75	2.56	0.21
General health	29.37	8.93	27.42	7.06	0.62

3.1. The general health status of the laborers

3.2. Sound pressure level (SPL) in working and rest stations

What Table 4 is standing for are the average and standard deviation of sound pressure level (SPL) in both working and rest stations, mean SPL and per-centage of the dose of received voice were 83.38±5.58, 81.49±6.33, 67.83±4.51, 82.44±5.28, 82.93±5.28 dB; and 62.4±278.09 respectively. These results show that mean SPL and dose of re-ceived voice (in %) were laid in the standard zone; however, in some cases, those were higher than allowed level.

Table 4
Noise conditions of vocational sites and received dose in the laborers

Variable Minimum Maximum Average Standard deviation

SPL of site 1 53.2 99.3 83.38 5.58

SPL of site 2 70 95.7 81.49 6.33

Sound pressure in rest times 55.2 82 67.83 4.51

Equivalent level of sound exposure (Leq) 72 97 82.44 5.25

Mean SPL 72 98 82.93 5.28

Percentage of received dose 5.64 1783 62.4 278.09

Variable	Minimum	Maximum	Average	Standard deviation
SPL of site 1	53.2	99.3	83.38	5.58
SPL of site 2	70	95.7	81.49	6.33
Sound pressure in rest times	55.2	82	67.83	4.51
Equivalent level of sound exposure (Leq)	72	97	82.44	5.25
Mean SPL	72	98	82.93	5.28
Percentage of received dose	5.64	1783	62.4	278.09

3.3. Correlation between SPL and general health and related subscales

Results being extracted from statistical analysis among SPL, measured dosimetry, general health scores, and related subscales have been shown in Table 5. According to these outputs, a significant positive correlation has been observed between mean SPL and received dose percentage. By contrast, there was no significant correlation between SPL in rest time and general health.

Table 5
General health and its subscales correlation with investigated indices in the vocational site of the laborers

Variable Statistical analysis General health (total) Physical health Stress and insomnia Social function Depression

SPL of site 1 Correlation 0.214 0.297 0.137 0.179 0.05

P-value 0.001 0.000 0.03 0.006 0.41

SPL of site 2 Correlation 0.214 0.347 0.162 0.177 0.12

P-value 0.000 0.000 0.014 0.007 0.06

Sound pressure in rest times Correlation 0.06 0.04 0.013 0.003 0.09

P-value 0.34 0.47 0.84 0.96 0.14

Equivalent level of sound exposure (Leq) Correlation 0.232 0.314 0.169 0.177 0.06

P-value 0.000 0.000 0.01 0.007 0.3

Mean SPL Correlation 0.211 0.296 0.162 0.168 0.03

P-value 0.001 0.000 0.01 0.011 0.5

Percentage of received dose Correlation 0.164 0.184 0.109 0.157 0.06

P-value 0.01 0.005 0.1 0.01 0.29

Variable	Statistical analysis	General health (total)	Physical health	Stress and insomnia	Social function	Depression
SPL of site 1	Correlation	0.214	0.297	0.137	0.179	0.05
	P-value	0.001	0.000	0.03	0.006	0.41
SPL of site 2	Correlation	0.214	0.347	0.162	0.177	0.12
	P-value	0.000	0.000	0.014	0.007	0.06
Sound pressure in rest times	Correlation	0.06	0.04	0.013	0.003	0.09
	P-value	0.34	0.47	0.84	0.96	0.14
Equivalent level of sound exposure (Leq)	Correlation	0.232	0.314	0.169	0.177	0.06
	P-value	0.000	0.000	0.01	0.007	0.3
Mean SPL	Correlation	0.211	0.296	0.162	0.168	0.03
	P-value	0.001	0.000	0.01	0.011	0.5
Percentage of received dose	Correlation	0.164	0.184	0.109	0.157	0.06
	P-value	0.01	0.005	0.1	0.01	0.29

Statistical analysis showed that there was a significant positive correlation between SPL, mean SPL and percentage of the dose of received voice; whereas, there was no significant relationship between general health and SPL in rest time.

There was a significant positive correlation be-tween social function and SPL indices in working stations; and likewise between mean SPL and received dose percentage. Conversely, there was no significant positive correlation between social function and SPL index in working stations related to rest times; however, depression and SPL in working stations and similarly mean SPL and received dose percentage are positively and insignificantly correlated.

4. Discussion

The labor seems to be the most critical capital in every industry. Having a healthy vocational site (without excruciating parameters) can leave the door open for the economic boom [19, 20]. The current study is aimed to assess occupational noise exposure as a parameter overshadowing the general health, and examine the general healthy condition of a 500 laborers group. First and foremost, results showed that the average of general health scores is laid mostly in the critical zone (upper than 23); in similarity study, approximately 48% of the studied laborers do not possess general health condition. Although some subscales such as physical health, stress and insomnia, and social function are in the normal status [19 , 22], they are not something so suitable; this might be owing to deleteriously-influencing occupational noise exposure on people’s bodies, especially on their hearing system. Moreover, occupational noise exposure has undergone laborers’ rest and sleep. Having posed in noisy conditions, many laborers were confronted a sleep disturbance [23, 24]. Additionally, the social function of this 500-member group has vividly been affected. Although depression subscale is not entirely desirable, it has a better situation in contrast with other subscales. Overall, general health scores recited that laborers do not have a proper general health condition as against other studies being conducted [25 –27]. This might stem from not having job security, bad financial status, economic recession, and unemployment.

Simultaneously, extracted results are reciting that general health parameter is far more proper among bachelors over against married people; though, there is no significant relationship between general health scores and marital status. This might be because bachelors never exposed with a role named ‘breadwinner’; more importantly, this result has been confirmed by previous studies [28]. Additionally, in those industrial sites, the level of noise that the mentioned workers are exposed with is more than the REL being determined by international regulations [14]; apart from this, they mostly work long hours more than of what defined in their organizational chart. Besides these abnormal conditions, they are allowed to rest just for 58.8 minutes (less than one hour); consequently, thanks to these parameters, they would be exposed with SPL 84.44 dB.

According to the results of the current research, there is a positive significant correlation between the following parameters: general health and its subscales and SPL in working sites; mean SPL and re-ceived dose percentage. It was corroborated that increasing in general health scores would accompany with a sharp decrease in their general health conditions; this result used to be confirmed by previous studies [25 , 28]. SPL in rest times and general and physical health are positively correlated, but insignificantly.

There is a positive significant relationship between stress and insomnia and SPL. As being low of general health score is an emblem of laborers’ health; consequently, rising SPL in those vocational sites would associate with reducing general health conditions (i.e. jumping general health scores). Thereby, increasing the mentioned scores would be conducive to exacerbating sleeping disturbance [9 , 28].

Based on the results of the current research there is a positive significant correlation between the following parameters: social function and SPL in workplaces; mean SPL and percentage of noise dose received. A lower general health score is the emblem of high-level laborers’ social function; consequently, going up SPL in those work sites would result in plummeting the level of social function (i.e. jumping social function scores). Hence, by increasing the mentioned scores, the social function would be exacerbating [21 , 28].

The Depression is positively but insignificantly correlated with all indices of SPL: mean SPL, received dose percentage, and SPL in rest times. This result contradicts those of previous studies [10, 28]. Of the most obstacles getting us confined were difficulties in coordination and also antagonistic cooperation of some of the managers.

5. Conclusion

Based on the results of this study, occupational noise exposure in these industrial units had effected on the general health of workers. As general health scores and its sub-scales in these workers are in an inappropriate state and noise has an inappropriate effect on public health. Therefore, it appears that in these industrial units due to exposure to noise and inadequate working environment conditions, the health status of workers has an inappropriate situation. If in the future, prevention programs in the work environment are not implemented, a high percentage of them would be lose their health.

Conflict of interest

The authors have no conflicts of interest to disclose.

Footnotes

Acknowledgments

The current article is the output of the project supported by the Research Deputy of Kurdistan University of Medical Sciences, Iran (No. 1394.3.5-94.25). The authors would like to express their gratitude to the Research Deputy of University of Medical Sciences of Kurdistan, the laborers working at the industrial site of Sanandaj, and those who helped us during this process.

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