چكيده لاتين :
Background and aims: Noise exposure as a main problem of industrial world is one of the most
common risk factors in industries and many employees expose to it in the workplace. Noise exposure
causes a wide range of the discomforts, disorders, and occupational diseases and effects including focus
loss, systolic blood circulation changes, sleep disturbances, long-term memory loss, Anger, vascular
problems, stress, headache, nausea, irritability, and irreversible hearing loss. Hearing loss in industrial
environments is made due to the prolonged exposure with the high level sound pressures and considered
as the agent of one third of occupational diseases in Europe. One of the most current and important
industries with high level sound pressures in Iran is oil and gas industry. Iran has a special status in
terms of oil and gas resources in the region and world, so that it is considered as the fourth crude oil
producer, fifth crude oil exporter, and third country having oil reserves. This industry provides the
material and energy to other industries and can play a substantial role in economics of developing
countries. Abadan oil refinery is largest refinery of Iran and one of three largest refineries in the world.
This refinery has been located in Khuzestan province of Iran and occupational noise in mostly its units
has exposed the employees to adverse health effects. The results of various studies performed on
physical harmful agents, particularly noise, in the oil and gas industry and related companies indicate
that noise exposure in some their units is higher than acceptable limit in some units. Given the special
status of oil industries and the high volume of labor forces in these industrial units, the present study was
aimed to evaluate the workplace noise in operational units of reservoirs and petroleum products
transportation of Abadan oil refinery and investigate the impact of control measures on the noise
exposure.
Methods: This cross sectional and analytical study, was carried out in the operational units of tanks and
petroleum products transportation including Crude oil pumping stations 1, 2, and 3, pus oil pumping
station, MTBE, Control Center, NTA, KTA, mixing and fusion, fuel transportation, spherical reservoirs,
and mazut unit. At the first, the basic information including locations of noise sources and operating
conditions of equipment in the various units were collected for determining the noise pollution and
identifying the noise productive resources. Then, the values of the sound pressure level were measured
using sound level meter, model CEL 490, made by Casella company based on ISO 9612 standard. As
well as, the sound level meter was calibrated by the calibrator, model CEL-110/1. In addition, the noise
characteristics of the productive resources were determined by ISO 3745 standard. Based on ISO 9612
standard, the studied units were divided to equal squares with the dimensions of five and five meters
using a regular network measurement pattern and the centers of these squares were specified as the
measurement points. Given that the noise variations were lower than five dB, the values of the sound
pressure level were measured at least three times in each point and their mean were calculated as the
sound pressure level of each point. The least time of noise measurement in each point was fifteen
seconds. To identify the main noise productive resources and dangerous areas with high sound pressure
level, the measurement results were depicted in the form of a noise plan. The mean values of air temperature and relative humidity during the measurements were 38 degrees of centigrade and 64
percent, respectively. As well as, wind speed was slow. Give the aim of study, network A was selected
as sound level measurement weighting scale and mean height of sound level meter from ground surface
was nearly 1.55 ± 0.175 meters. After identifying the main noise productive sources in the units, control
measures including were determined and implemented based on the type of the noise source. The used
control solutions included lubrication of moving parts, repairs, improvement of pumps foundations,
reduction of exposure time, and, use of personal protective equipment during exposure to the noise.
Based on the type of the noise source, one or combination of control solutions were used. and
measurements were carried out in controlled areas. Finally, after performing control measures, the remeasurement
of sound exposure in similar situations was carried out in units. In final, the noise
measurements were repeated again after performing the control measures based on the stated method.
Results: In total, 11 units were investigated in this study. The results of environmental noise pollution
measurement in the operational units of reservoirs and petroleum products transportation showed that
NTA unit with the mean sound pressure level equal to 89.28 dB and spherical reservoir unit with the
mean sound pressure level equal to 75.33 dB have the highest and lowest values of the noise pollution,
respectively. Based on the results, of 523 measured stations in the present study, 115 stations were with
a sound pressure level more than 85 dB, 373 stations with a sound pressure level from 65 to 85 dB, and
30 stations with a sound pressure level less than 65 Db. Of the total measured stations, 71.3 percent are
in alert zone, 21.9 percent in risk zone, and 5.7 percent in safe area. NTA unit had the most number of
the stations higher than 85 dB and KTA unit had the least number of the stations less than 85 dB. Of
total stations with the sound pressure level higher than 85 dB, 19 percent was related to control center
unit, 4.54 percent related to KTA unit, 9.37 percent related to crude oil pumping station 2, 27.5 percent
related to crude oil pumping station 3, and 34 percent related crude oil pumping station 1. The results
determined that the control measures decreased the mean sound pressure level of crude oil pumping
station 1 by 2.39 dB, of control center unit by 1.7 dB, of pus oil pumping station and MTBE units by
0.89 dB, and of NTA by 0.08 dB. As well as, the results of the measurements indicated that the sound
pressure level of other units did not significantly change.
Conclusion: The results showed that the highest and lowest values of the sound pressure level were
related to NTA unit and spherical reservoirs unit, respectively. The most inappropriate stations with the
high noise pollution were related to NTA unit. This unit have a great importance among studied units
because of the number of people exposed to noise and the value of noise pollution. Given the
environmental measurement results, units with a mean sound pressure level higher than 85 dB require
the corrective actions, particularly technical engineering measures and effective control strategies, for
the continuous improvement. Based on the measurement results, 115 stations have the values of the
sound pressure level more than 85 dB. If the engineering and administrative control measures are not
implemented, the exposure time should be reduced. The results of the present study indicated that the
implementation of the low-cost control methods and the repair and maintenance of the equipment and
devices can decrease the noise exposure. In addition, these control measures increase the mean allowable
time exposure. These results suggest that the appropriate control measures can cause the optimal use of
the workers and professionals in different occupations. Refineries are one of the industries that most
parts of it produce the noise pollution. As well as, because of the number of employees, exposure to a
variety of harmful agents, and difficult environmental conditions, the control measures such as
engineering solutions in oil and gas refineries should be given more attention. To reduce the noise
exposure in the operational units of reservoirs and petroleum products transportation, the following
control solutions are proposed. The maintenance, repairs, and proper lubrication of the machinery and
equipment will reduce the unwanted noise production. It should be noted that the machinery
maintenance and repairs not only are necessary for the noise control, but also increase the useful life of
the machinery. Vibration also is one of the noise productive sources. Vibration can be controlled using
the appropriate foundation, rubber layers, and etc. This solution will reduce the sound pressure level
generated by the vibration. As well as, the appropriately choice of the machinery or equipment reduces
the level of the unwanted noise. The selection of the machinery with the most consistent and with the
lower levels of the undesired noise production due to higher technology are considered as key factors in
the strategies to minimize the unwanted noise. Prohibiting or restricting the use of the noise productive
equipment can significantly diminish the unwanted noise. In addition, given to 12-hour planning of the
staff shift work and the mean value of the sound pressure level in the operational units, job rotation can
be effective. Finally, the hearing protective equipment as the latest solution of the unwanted noise
control can be applied. If this control measures are correctly implemented, those can greatly reduce the
noise pollution and ensure the increase of the employees’ health and productivity.
