A case study of construction noise exposure for preserving worker s hearing in Egypt

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1 TECHNICAL REPORT #2011 The Acoustical Society of Japan A case study of construction noise exposure for preserving worker s hearing in Egypt Sayed Abas Ali Department of Architecture, Faculty of Engineering, Assiut University, Assiut, Egypt ( Received 18 October 2010, Accepted for publication 31 March 2011 ) Abstract: Every day, approximately half a million workers in the construction sector in Egypt are exposed to excessive noise. Noise is one of the most prevalent physical contaminants in the construction sector. The most negative effects of noise exposure are related to the hearing system and may produce occupational deafness or even permanent deafness. These effects have a very important influence on people s health and well-being. The goals of this study are to carry out measurements to evaluate construction noise levels, which exceed the permissible level set by Egyptian noise standards and policy to protect the public health of workers, to assess noise exposure, and to develop controls for proposing preventive solutions. The noise levels to which the workers in the construction sector are exposed have been studied. A number of representative measurements have been carried out using a sound level meter and a dosimeter to collect data from workers devoted to different tasks in the construction process. The most important levels and indexes have been analyzed with those data. Keywords: Construction workers, Noise exposure, Noise control, Egypt PACS number: Gf [doi: /ast ] 1. INTRODUCTION Unlike other contaminant agents, the effect of excessive noise may not be noticed immediately and its accumulation can lead to obvious physical, psychic and social deterioration. The ultimate effect of overexposure to noise is the loss of hearing. The problem is that exposed people are rarely aware of the cause-effect relation because it advances slowly but progressively. Every day, half a million Egyptian workers are exposed to excessive noise and to all its consequent risks in their workplace [1]. A worker in Egypt may need to raise his voice to be heard for more than half the working day and thus suffers from hearing problems related to work [2]. Noise is a definite problem in sectors such as manufacturing and construction. The most obvious parameter to characterize noise can be its level, but there are some other important factors to take into account, such as duration of exposure, impulsivity, frequency and spectrum and incidence and distribution during the working day [3,4]. Noise exposure can cause several risks to the safety and health of workers. It is well known that noise can mask both, speech and alarm sounds. Speaking problems, such as nodules, loss of voice, and abnormalities in the vocal sayed142@yahoo.com chords, can be suffered by workers that have to communicate within noisy environments of noise levels higher than 90 db if there is no other way to communicate. It is stated that noise is one factor that can increase the risk of accidents in the workplace. Furthermore, the effects of noise-induced hearing loss, together with the requirement of using hearing protection devices, indirectly contribute to increase in the rate of accidents owing to interference with sound signals and other non-hearing effects caused by noise on the health, such as stress, loss of attention, and increased blood pressure [5,6]. The removal of noise excess in the workplace is not just a legal responsibility of the companies since as it is also related to the market interests of an organization. The safer and healthier a workplace is, the fewer probabilities of absenteeism, accidents, and low performance, and consequently, cost savings will be achieved. The reduction of risks due to noise in the workplace is three-step process: assessment of risks; adoption of control for preventing or controlling risks; and, eventually, maintaining periodical monitoring and revision of the effectiveness of the adopted control. The goals of this study are to carry out measurements to evaluate construction noise levels, to determine whether these levels exceed the permissible levels set by Egyptian noise standards and policy designed to protect the public 211

2 Table 1 Maximum daily exposure duration to noise levels set by Egyptian law [7]. Noise level (db) Period of exposure (hour) /2 1/4 health of workers, to assess noise exposure, and to develop noise control for the proposed preventive solutions. 2. METHODS 2.1. Egyptian Regulations The current regulations in Egypt regarding the protection of workers are based on environmental law No 4 for year Intensity of noise (A-weighted time-average sound (pressure) level of noise) must not exceed 90 db during a daily 8-hour work shift. 2. In the case of increasing noise level over 90 db, the period of exposure must be reduced according to Table The instantaneous noise level (C-weighted peak sound (pressure) level) during the working hours must not exceed 135 db [7]. 4. In the case of exposure to different noise levels of over 90 db: (1) For intermittent periods during a shift, the result must not exceed ða1 þ A2 þ...:þ over the integer one B1 B2 where A the period of exposure to a specific level of noise (hour) B the permissible period of exposure at the same noise level (hour) 5. In the case of exposure to intermittent noise emission from sledgehammers of foundations: depends on the exposure period (number of impacts during the daily shift) according to noise level as shown in Table 2. Noise issuing from sledgehammers must be considered intermittent if the period between impacts is one second or more. If this period is less, the noise must be considered continuous and is subject to the preceding items. The law does not stipulate whether noise control should be applied Scope of the Study There are several noise sources in the construction sector, which cover all the stages of construction work. Noise is different in each one of these stages, but, nevertheless, sometimes the same worker may be present in more than one stage, and therefore, we are more Table 2 Number of permissible impacts during one daily shift in accordance with noise level (db) set by Egyptian law [7]. Number of permissible Noise level (db) impacts during the daily working hours , , , ,000 interested in the construction work in general than in each individual stage. Twenty-one different construction sites have been studied (three sites for every stage). Common construction work in Egypt, on the basis of a concrete structure, comprises the following stages. Stage 1. Excavation and land movement.. Stage 2. Foundations and structure.. Stage 3. Walls and brickwork.. Stage 4. Paving and tiling.. Stage 5. Facilities: electricity, drainage, plumbing, heating.... Stage 6. Carpentry and finishing.. Stage 7. Auxiliary activities and those of loading and unloading Measurements Whenever possible, measurements must be done in the absence of the affected worker by placing the microphone at the same height as his ear. If the worker must to be present, the microphone will be placed preferably in front of his ear, at a distance of approximately 10 centimeters. For this study, an integrating and averaging sound level meter with a spectrum analyzer has been used in order to obtain data related to the frequency components of the noise measured, given that this information is very useful, for instance, for choosing the most suitable personal hearing device should it be necessary. A logging dosimeter has also been used to measure the noise exposure during the working day without interfering with the worker, given that the dosimeter can be placed in a pocket or on the belt. The microphone must be placed at a distance between 10 and 30 centimeters from the ear, for instance, in a lapel or over a helmet. As the microphone is linked to the dosimeter with a cable, it must be carefully placed so as to avoid any risk to the worker. The effective measurements were made using the dosimeter (worn by the worker) and the sound level meter (very closed to the worker) simultaneously. The first measurements taken at a construction site were disregarded to avoid any deliberate influence and so that the workers at the site could get used to the measurement procedure. 212

3 S. A. ALI: A CASE STUDY OF CONSTRUCTION NOISE EXPOSURE FOR PRESERVING WORKER S HEARING IN EGYPT Noise Level Noise level Fig. 1 Measured daily equivalent level for each worker L Aeq (db). 1 3: Excavation and land movement, 4 6: Foundation and structure, 7 9: Wall and brickwork, 10 12: Paving and tiling, 13 15: Facilities: electricity, drainage, etc, 16 18: Carpentry and finishing, 19 21: Auxiliary activities, loading, unloading Fig Peak level for each worker measured L C peak (db). The registered parameters either with the sound level meter or with the dosimeter are. equivalent continuous A-weighted sound pressure level, registered along the whole measurement (L Aeq;T in db), as shown in Fig. 1,. peak level registered during the entire measurement (L C peak in db), as indicated in Fig. 2,. noise dose (D in %), as shown in Fig. 3,. spectrum from 12.5 Hz to 20 khz, as illustrated in Fig. 4. A threshold (TH) of 75 db, a critical level of 85 db, an exchange rate (ER) of 3 db and a duration of 8 h for the working day have been used for the exposure and dose measurements A - weighted sound pressure level db Noise Dose (%) for T = 8 h Fig. 3 Measured daily noise dose for each worker Frequency (Hz) With machines Without machines Fig. 4 Noise a spectrum suffered by workers that must use machines in their tasks and by workers that rarely use machines in their tasks. From the indexes measured, other ones are revealed, which are necessary for their comparison with the limits established by current regulations, as in the case of the daily sound exposure level L Aeq;d. The duration of the measurement was stated for assessing the target workers. It should be sufficient to characterize properly the noise measured for each worker. Normally, a duration of 8 h is assumed for L Aeq;d. Furthermore, the duration could be reduced even to only 30 min. In the case of impulsive noises, it was checked that they were repeated periodically during the whole working day in order to ensure the parameters of the measurement time Measurement Record A technical record has been registered for each worker measured, where the most important data and the results of processing the data from the dosimeter and the sound level 213

4 meter are recorded. The records comprise a brief description of the worker s tasks and technical parameters, which are indispensable (L Aeq;d and L Cpeak ) for the comparison with the current regulation, noise dose and noise exposure in the duration of the measurement. In addition, to make the results more realistic, two parameters have been added: the noise dose calculated for 6 h of the working day instead of 8 (to take into account the breaks) and the maximum allowable time of exposure for a worker to receive a dose of % of the measured noise. The record also includes different plots of the measured data, such as the time evolution of the signal, the spectral trace, and the distribution of the levels. Finally, the record also includes observations and data of interest regarding each occupation, such as the requirement of using machinery for the tasks or the continuous time that a machine is operating on Instruments The experimental data in this study have been obtained with one integrating and averaging sound level meter with a spectrum analyzer (Brüel & Kjær Investigator 2260), one unit of a noise logging dosimeter (Brüel & Kjær type 4445) and one sound calibrator (Brüel & Kjær type 4231). The sound level meter has the following specifications.. Range: db.. Bandwidth: 1/3 octave.. Peaks over 140 db. Global statistics: Time weighting F (Fast) and Frequency weighting A (A-weighting).. Spectrum: Time weighting F (Fast) and Frequency weighting A (A-weighting).. Global measures: Frequency weightings A&L.. Logging: 1 record/minute. The specifications of the dosimeter are the same as those of sound level meter with the following additions.. Frequency weighting for peak - C.. Exchange rate: 3 db.. Threshold: 75 db.. Criteria level: 85 db. Two different software from Brüel & Kjær have been used for obtaining and processing the measurements. One of these software packages has been used for post processing and archiving noise exposure data recorded with the dosimeter; it performs the calculations according to ISO In addition, another software package has been used for post processing, preparing graphics and tables, and archiving measured levels and spectra taken with the sound level meter; it adheres to ISO1996, which the calculations follow. Both software produced the same results regarding the global levels, with a slight tolerance of no more than 2 db, after processing the recorded data; hence the measurement procedure and the results of the measurements are again confirmed. Noise dose is given in terms of Table 3 Measured and calculated parameters. No. Stage L Aeq (db) L Cpeak (db) Dose (8h) (%) Tmax ðd¼þ h ,291 > ,820 > > , , , > > > > > a value relative to unity or % of an acceptable amount of noise. In the UK, an exposure to a sound level of 85 db for 8 hours is equivalent to a % noise dose [8,9]. 3. Results Results of the measurements are summarized in the Table 3, where the main parameters for the 21 workers assessed, are given: daily equivalent A-weighted level, C-weighted peak level, and the noise dose for an 8-hour working day, such noise during the working day for a noise dose of %. The noise environment to which a construction worker is subjected can be derived from the analysis of those data. The daily equivalent A-weighted level is shown in the chart in Fig. 1. It clearly shows that most of the workers, 14 out of 21 (66.7%), suffer a daily exposure that exceeds 85 db. However, what is worse is that 13 out of 21 workers, 61.9%, that are subjected to more than 90 db, which is the top limit, stated explicitly that they needed machines to perform their tasks. The chart in Fig. 2 shows C-weighted peak levels. There are 6 out of 21 workers, 28.6%, that are subjected to noise peaks over 140 db; one of them works in stage 1 (excavations and land movements), 2 of them work in stage 2 (foundations and structure), and 2 of them work in stage 4 (paving and tiling). The chart in Fig. 3 shows the dose received by each worker. There are extremely high values, as the graph and the table reveal, that exceed 400%. Most of the workers are exposed to doses that exceed the maximum level of %. 214

5 S. A. ALI: A CASE STUDY OF CONSTRUCTION NOISE EXPOSURE FOR PRESERVING WORKER S HEARING IN EGYPT This indicates that the construction workers are exposed to too high a dose that is maintained over prolonged period of time. Stages can be analyzed individually. For instance, in the sixth stage of carpentry and finishing, the noise dose is below %, which is acceptable. The highest dose occurred in the first stage of excavation and land movement and in the second stage of foundations and structure. An average A-weighting equivalent level of more db is obtained, which is very high for the peak noise, and all the workers are exposed to an extremely high, dose that can be very harmful to the worker s health and consequently. There has been an attempt at differentiating the assessed workers into two sets: the workers who must use machines continuously in their tasks and workers who may rarely use machines. The results given in the Fig. 4 indicate that through the average spectrum measured for both sets, despite the great difference of levels, all the occupations that require machinery have the common characteristic that the level increases as the frequency increases, probably because most of the machines have frequency components of noise emission in the highfrequency range. On the other hand, the workers that do not require machinery are exposed to noise that has a spectrum that decays at high frequency. 4. DISCUSSION In general, from the data in Table 3, it can be stated that the sound environment which the construction workers are with is quite noisy and potentially harmful to their health, since the top limit of 90 db is exceeded in most cases, and more over, the percentage of cases that exceed the top limit of 90 db is quite high. Measurements obtained in this study, such as those presented in Fig. 3, indicate the measured daily noise dose for each worker. Figure 4 illustrates the noise a spectrum suffered by workers that must use machines in their tasks and by workers that rarely use machines in their tasks. In this study, in addition to the noise dose, the peak level and the spectrum have been taken into consideration. 5. CONCLUSIONS AND REMARKS The noise levels that construction workers are exposed to were analyzed. The number of measurements is representative of the real number of workers in Egypt where the study were carried out. The main conclusion that can be obtained is that there are high noise levels for any working environment related to construction (noise levels ranged from 82.1 db to 112 db). These are so high that 81% of the construction workers are exposed to a noise dose higher than % during their working day. In the stage of carpentry and finishing, the noise dose is below %, which is acceptable, whereas the highest dose occurs in the stage of excavation and land movements and in the stage of foundations and structure. The low awareness of the workers and the companies regarding excessive noise exposure and their consequences is astonishing. ACKNOWLEDGEMENTS The author is grateful to Egyptian construction companies for their help in carrying out this study. This study was financially supported by the Egyptian Ministry of Higher Education. REFERENCES [1] General annual Egyptian Statistics for 2009 (2009). [2] U. Ahrlin, Activity disturbance caused by different environment noise, J. Sound Vib., 127, (1998). [3] W. Utley and A. Miller, Occupational noise exposure on construction sites, J. Appl. Acoust., 18, (1985). [4] D. Marcos and Q. Samuel, Noise exposure of workers of construction sector, J. Appl. Acoust., 70, (2009). [5] Anon, Exposure of construction workers to noise, Construction Industry Research and Information Association, UK (1984). [6] J. Sinclair and W. Haflidson, Construction noise in Ontario, Appl. Occup. Environ. Hyg., 10, (1995). [7] Egyptian environmental law No. 4 of year 1994, Egyptian Ministry of Environment, Egypt (1994). [8] G. Ritterbusch and K. Meitl, Thirty years of governmental limits for construction machinery, Noise Control Eng. J., 49, (2001). [9] Health & safety executive in UK. hse.gov.uk/noise 215