Introuduction
Studies have shown that 16% of hearing loss is occupational and caused by noise in the work ‎environment. Also, about 0.2 to 2% of the gross domestic product in developing countries is ‎spent on expenses caused by noise, and about a third of hearing loss is caused by exposure to ‎excessive noise. Fortunately, in Iran, more attention has been paid to noise pollution in recent ‎years; So that according to Article 2 of the Executive Regulations related to how to prevent ‎noise pollution, since 1378 it has been prohibited to take any action that causes noise pollution ‎‎[7]. Sound pollution control, which is very important today, is important in the first step of ‎measuring the level of sound pressure and comparing it with the standard (85 dB for 8 hours ‎of work). According to the studies conducted by the researchers of this project, at least one ‎million workers in the country are exposed to noise exceeding the permissible limit, among ‎which the exposure of workers to noise in workshops such as stone cutting, carpentry, welding ‎and turning is significant. is Also, with the increasing progress of industry and industrial ‎technology, the need to investigate the risk factors of the work environment, including sound, ‎which is considered as the most common physical harmful factors in the work environment, ‎has been felt more and due to the increase in the diversity of the risk of injury. This factor is ‎necessary for workers to compile basic information for the study of the situation of exposed ‎groups and hearing protection programs [3]. The purpose of hearing protection programs in the ‎workplace is to prevent the occurrence of The onset and progression of hearing loss is caused ‎by exposure to noise in workers. In America, after recognizing hearing loss as a health ‎problem, OSHA announced guidelines that included the minimum principles and regulations ‎necessary for employers to establish them in the work environment. Although the ‎implementation of these principles alone does not guarantee the full effectiveness of this ‎program in preventing hearing loss. The employee hearing protection program consists of 5 ‎steps, which are: regular sound check, implementation of engineering or administrative ‎methods in order to establish permissible limits, training, use of personal protective equipment, ‎evaluation through audiometry in the workplace. Depending on the case, the implementation ‎of one of the above steps can be emphasized more. But in general, the implementation of all 5 ‎steps is essential and effective [1]. Most of the sawmill workers employed in this study were ‎men. Although blood pressure was unknown before recruitment, it is assumed that many of ‎them had normal values. Some of the factors known as risk factors for high blood pressure are: ‎family history of high blood pressure, increasing age, sedentary lifestyle and diet. However, ‎this study is focused on the effects of long-term noise exposure on blood pressure in Bandar ‎Anzali lumber mill workers.‎
Materials and Methods
The study area: Bandar Anzali is connected to the Caspian Sea from the north, Soumesara ‎City from the south, Rasht City from the east, and Razvanshahr City from the west. Bandar ‎Anzali City is located in a completely plain area along the coast of the Caspian Sea. The ‎present study is a descriptive and analytical type that was carried out in the wood-cutting ‎workshops of Bandar Anzali city. In this research, 65 employees of the lumber workshop of ‎the city were selected and statistical sampling was done using Cochran's formula, based on ‎this formula, the statistical sample number of 52 employees was selected as a cluster from ‎several available workshops.‎
The information of all subjects under study, including demographic information, medical ‎records, and job information was obtained using the direct interview method and recorded in ‎a questionnaire that was designed for the implementation of this study. The information in this ‎questionnaire included: age, work experience, medical history, duration of exposure to the ‎device, proximity to the device, blood pressure before work, blood pressure after work, and ‎sound intensity measured on site. The data obtained by SPSS 20.0 statistical analysis software ‎were calculated and to check the reliability of the questionnaire, Cronbach's alpha test was ‎considered with the acceptance condition of the test result above 0.7. Pearson's correlation test ‎was used to determine the significance of the relationship between research variables.‎
Results
In this study, 78.85% (41 people) of these employees did not have a history of hypertension, ‎while 21.15% of these people (11 people) had a history of hypertension. To check the ‎reliability of the questionnaire, Cronbach's alpha test with the acceptance condition of the test ‎result above 0.7 is considered, and the results of the test analysis are 0.86, which indicates the ‎acceptable reliability of the questionnaire.‎
The secretaries in the sawmill workshop are not directly connected to the machines and are ‎mostly working in a separate room, that's why the sound intensity is low for them (the average ‎sound intensity is approximately 67 dB). And the amount of changes in their blood pressure, ‎after and before work, is almost zero. However, the amount of changes in the blood pressure ‎of these people and also the level of sound intensity in the rooms of these people depends on ‎the distance of their work room from the workshop and the proximity to the type of machine. ‎To investigate the existence of a relationship between these three factors in the sawmill ‎workshop. Pearson's correlation test was used to check the relationship between the three ‎variables. According to Table 3-4, the value of sig indicates the existence of a relationship ‎between three variables. Because the value of sig is less than 0.05, as a result, there is a ‎significant relationship between the three variables.‎
The results obtained from the data analysis of the lumber workshop indicate that there is a ‎significant relationship between blood pressure before work and blood pressure after work. ‎While there is no significant relationship between any of the variables of age, working hours, ‎having a history of hypertension, and blood pressure after logging. Also, according to the ‎number of hours, the workers are exposed to the devices and the number of changes in their ‎blood pressure, it can be said that there is a difference between the exposure of people ‎between 5-6 hours and 7-8 hours of exposure of people to the devices in the lumberyards. It ‎does not exist, and on average, each device raises people's blood pressure by 1.01. Due to the ‎low level of sound intensity in the secretary's office (the average sound intensity is ‎approximately 67 decibels), the amount of blood pressure changes after and before work is ‎zero. However, the amount of blood pressure changes in these people as well as the sound ‎intensity of these people's rooms depends on the distance of their work room from the ‎workshop and the proximity to the type of device. ,‎