Effects of Occupational Noise Exposure On Arterial Blood Pressure, Pulse Rate, and Hearing Threshold Levels in Workers in Selected industrial Plants in Nablus City

Discussion Committee: 
Prof. Mohammed S. Ali-Shtayeh- Supervisor
Dr. Issam Rashid Abdel-Raziq- Co- Supervisor
Dr. Issam Al- Khatib- External Examiner
Prof. Ibrahim Wahdan- Internal Examiner
Hanini, Nazim Sa'd Abdel-Rahim
Two hundred and eight (208) male workers from eight industrial plants in Nablus city were monitored for noise exposure during a normal work shift. All subjects had no history of heart or hearing disorders. The mean age of subjects is 34.85 ± 2.43 yr. [mean ± standard deviation (SD)], and the mean duration of employment in the current -job is 8.55 ± 2.71 yr. [mean± SD]. The mean working hours in all study locations is 11.25±1.04 hr/day [mean 1 SD]; 10 hr/day in 37.5 % of studied industrial plants and 12 hr/day in 62.5 % of them. The working hours in all studied industrial plants are more than 8hr/day as most international regulations recommended. Resulting equivalent continuous sound pressure levels (SPL) in dB(A) [LAC.] - values] in all studied plants ranged from 77.4 to 92.4 dB(A),with an arithmetic mean value of 84.43 J; 4.34 dB(A) [mean i SD]. The noise mapping performed at most of these plants showed that for most part of working hours, the noise levels exceeded the permissible levels set by the international standards. Results of the audiometric examinations showed that the hearing threshold levels (HTL) were significantly higher than permissible international standards at most frequencies. Strong positive correlation (Pearson correlation coefficient) [p < 0.05 and p < 0.01] was found between occupational noise pollution levels (NPL) and hearing threshold levels at most frequencies. Significant interactions were found between percentage of several degrees of hearing impairment [according to ANSI, OSHA, NIOSH & ASHA, and EPA’s definition] in both ears of subjects and occupational noise levels, age, and duration of employment. There are significant hearing threshold shifts in right and left ears of subjects in different locations, shortly before exposure to occupational noise and during exposure of at least 4 hours from the beginning of morning shift. IN this study, pulse rate (P.R), systolic and diastolic blood pressure (SBP & DBP) correlated positively (p < 0.05) with the occupational noise levels in most studied industrial plants. In addition, this work also showed that there are significant shifts in mean values of these variables shortly before exposure to occupational noise (pre—exposure) and during-exposure of at least 4 hours after work onset. Significant interactions were found between mean values of pulse rate, systolic and diastolic blood pressure, length of employment, and age of subjects. Based on the results of demographic and health status questionnaire. There is an association between exposure to high level of occupational noise pollution in long-term duration and feeling of nervous tension, low concentration, nausea, dizziness, migraine headache, hearing impairment, and muscle contraction, which are related to mental and physiological health effects. There are considerable differences between the frequency and percentage of feeling of mental [nervous tension, sleep disturbance] and physiological [hearing impairment] disease cases before and after receiving the current job. There is a relationship between work accidents and exposure to high levels of occupational noise as a source of annoyance, stress, and dissatisfaction. Many things can be done to mitigate occupational noise emissions and their impacts on human health in workplaces. Some of these are: shifting noisy sources away from residential areas, suppression of the occupational noise at the sources by shielding the source of noise generation, limiting the exposure time of the workers, following safety and health regulations, consider the noise consequences when designing factories’ building, and other actions which are recommended in chapter four of this study.
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