The Relationship Between Sound Pressure Level With Cognitive Failure Indicators and Noise Annoyance in a Ceramic Industry



Madvari RF^{1, 2} ; Dehghan SF³ ; Abbasi M⁴ ; Laal F⁵ ; Madvari AF⁶ ; Moradi FH⁷ ; Balochkhaneh FA⁸ ; Torshizi YF⁹ Show Affiliations
Source: Iran Occupational Health Published:2020

Abstract

Background and aims: The ceramics industry is one of the key industries in the economic development of any country. This industry has a large share of Iran's non-oil exports, so that in recent years it has consistently placed Iran's position in the production and export of this product among other developing countries. However, there are many harmful factors in these industries, which threaten the physical and mental health of workers. The most important factors are environmental hazards, cooling, heating, vibration, noise pollution, and so on. Noise pollution is very important in the ceramics industry, as in other industries. According to studies, about 600 million people worldwide and 30 million people in the United States face more than 85 dB noise in their workplace. According to a report by the Health Ministry's Workplace Health Center, there are about 2 million workers in Iran. . In addition, according to the National Institute of Occupational Safety and Health (NIOSH), 14 percent of the total workforce is working in environments with noise levels above 90 dB. Consequently, exposure to noise in the world, including Iran, is a problem in the workplace. Moreover, according to studies in the ceramics industry, it can be concluded that effects of exposure to noise is high for the employees of the industry. Kargar et al. demonstrated that about 45% of the ceramic industry's employees are exposed to noise above the permitted level. As a result, personal exposure to noise will be of particular importance to employees in the industry, based on the results of past exposure research. It is possible to work with noise in the workplace, except for hearing loss Hypertension, cardiovascular disease, gastrointestinal, behavioral, mental, and sleep disorders. On the other hand, acoustic disturbance is a new topic considered by researchers recently as one of the negative effects on one's health and comfort. The most common subjective response is measurable, and its effects may include physiological responses, central nervous system responses, and biochemical changes. These failures include various areas, such as memory, distraction, forgetfulness, and inadvertent errors. In addition, due to interference with daily activities, it can cause serious harm to the person. As a result, the present study investigated acoustic annoyance as the most common measurable subjective response among people exposed to noise and cognitive impairment as an indicator of one's ability to perform tasks that one is naturally capable of performing in a ceramic industry. At the same time, it is intended to examine the relationship between sound pressure level values with acoustic annoyance scores and cognitive failure. Methods: This descriptive-analytical study was conducted in the ceramics industry in 1998. To determine individual exposure to noise, the production sections and the annual results of the sound measurements were first examined, and then the loudspeakers were identified. In this study, the sample size was calculated using Cohen's sampling formula with 80% confidence interval of 95% confidence level of 96 people. Under 50 years of age, congenital hearing impairment, lack of sleep medications and CNS overdose, depression, and lack of a second job were considered. Thus, at the end of this study, after eliminating some of the study population, 50 workers were exposed and 50 administrative staff were placed in the control group. Also, volunteers were asked about the importance of the research subject. Then, to complete the questionnaires used in the study, a research session was held with the presence of the research population. Afterwards, the questionnaires were distributed to the individuals and their observation was completed. DOS 1354 TES was used to measure the sound pressure level. At the same time, the subjects completed a demographic questionnaire, noise annoyance, and cognitive impairment (CFQ) questionnaire. Measurement was done in two groups of exposure and control. The TES-1356 calibrator was manufactured in Taiwan to obtain the exact results of the equipment used before each measurement. In accordance with ISO 9612 standard, a dosimeter microphone was installed on their collar at a distance of 10-30 cm from the outer ear canal. At the end, exposure dose calculations were performed, as production workers were exposed to the same noise levels during the shift, and a two-hour dosimetry was performed and generalized to the equivalent of the 8-hour balance calculations. There were four components that had the first component of distraction (2 items), memory problems (7 items), inadvertent errors (7 items), lack of recall of names (2 items). The acoustic annoyance questionnaire consisted of three parts. These three sections included: The first part was heavily rated for workplace noise, the second and the third were respectively for workplace noise disturbance and for determining the situations people experience throughout the day, such as fatigue, lethargy, loss of concentration, and so on checked. The questionnaire was divided into 0 to 10 levels of annoyance, with (zero being non-annoying and 10 being excessive annoyance). The data were confirmed. Mann-Whitney test was used to analyze marital status with sound pressure level, acoustic distress, and cognitive impairment. In addition, Spearman test was used to correlate the parameters of sound pressure level, acoustic annoyance, and cognitive failure. The level of 0.05 was considered as the significant level. Results: The results of this study showed that 50% of the study population aged 27-33 years, 45% had a 3 -5 year work experience, 64% were married, and only 9% had university education. Qualitative analysis of both exposure and control groups showed that there was no significant difference between work experience, marital status, and education; however, there was a significant difference in age variable (p <0.05). Mean sound pressure levels in the exposure and control groups were 87.44±4.49 dB and 59.29 ± 3.02 dB, respectively. In addition, the score of acoustic annoyance and cognitive impairment in the exposure group were 70.65±10.65 and 63.74±8.67 and in the control group were 20.09 ± 2.90 and 45.14±8, respectively. Meanwhile, the highest and the lowest noise pressure levels in the exposure group were 95.78 dB and 64.50 dB, respectively. In addition, the highest frequency of acupuncture reported in the case group was 60% in the range of severe distress and 28% in the range of severe distress. However, the highest rate of acoustic annoyance in the control group was 68% in the non-annoyance range and 30% in the mild annoyance range. The results of the analysis of the third part of the acoustic annoyance questionnaire related to the situations that people experience during the day showed that the average experience of fatigue (3.38), fatigue and drowsiness (3.40), dizziness (3.46), decreased focus strength (3.58), headache (3.67) and more discomfort (3.57) compared to the control group. In addition, headaches (3.67) and fatigue (2.49) had the highest mean in exposure and control groups, respectively. The results of the statistical analysis showed that there was a significant positive relationship between the scale of acoustic annoyance and mood states (fatigue, lethargy and drowsiness, dizziness, loss of concentration, dizziness, headache, discomfort) (p <0.05). Also, Kruskal-Wallis test was used to assess the scale of acoustic annoyance with demographic characteristics.The results of Cognitive Failure Survey in the employees of this industry were analyzed in four sections and means of four sections of distraction, memory problems, inadvertent errors, failure to recall names in the exposure group were, respectively, 22.01, 20.60, 15.88, and 5.70. However, the mean of the four sections in the control group were reported to be 16.44, 13.92, 13.24 and 2.30, respectively. In addition, the mean correlation coefficient was upward (r=0.0778). There is a strong association between acoustic annoyance and memory problems and lack of recall. Also, the mean of cognitive failure was analyzed by age, work experience, marital status and education. The results showed that the highest rate of cognitive failure was in the age of 27-33 years, work experience of 3-5 years and cognitive failure in educated people was also less affected. Meanwhile, the relationship between sound pressure level and cognitive failure criteria showed a positive and significant relationship between them. There was also a significant relationship between Cognitive Failure Scale, acoustic annoyance and sound pressure level in both the exposure and control groups. (r = 0.768, p <0.05) Conclusion: The results of the present study confirmed that the noise level is higher than the recognized limit for hearing and mental health and consequently high levels of noise and cognitive impairment in ceramic workers. The most important outcome of acoustic disturbance in this population is a decrease in concentration, headache, dizziness, lethargy, and drowsiness that affect the physical and mental health of the individual and ultimately the productivity. Sound-induced annoyance followed by experience emotions, such as fatigue and loss of concentration increase the likelihood of human error and sometimes irreparable occupational accidents, which makes clear the importance of noise exposure levels in terms of health and workplace safety. Given the significant relationship between these factors and noise pressure levels, it is recommended to take appropriate measures to reduce workers' exposure to noise in the industry in order to maintain employees' mental health and increase their work efficiency. Also, considering the individual differences in the sense of distress, assessing people's sensitivity to noise for work in areas with high noise pollution can also help improve workplace conditions and prevent serious injuries in susceptible individuals. © 2020 Iran University of Medical Sciences. All rights reserved.