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Assessment of occupational noise exposure in coffee grinding shops
Applied Acoustics 158 (2020) 107047
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Assessment of occupational noise exposure in coffee grinding shops Omaimah Ali Al-Arja ⇑, Tala Samir Awadallah Department of Architecture and Interior Architecture, School of Architecture and Built Environment, German Jordanian University, Muath Bin Jabal Street, Jabal Amman, Amman, Jordan
a r t i c l e
i n f o
Article history: Received 12 April 2019 Received in revised form 13 September 2019 Accepted 17 September 2019
Keywords: Sound pressure levels Occupational noise exposure measurements Coffee grinding noise
a b s t r a c t This study investigates noise exposure for workers in coffee grinding shops CGS in the Arab Region. The investigation is conducted by identifying the levels of noise produced by coffee grinding machines, quantification of noise potential impacts on workers, comparison of measured values with local and international recommended average exposure values, and setting recommendations for better indoor working environment. Indoor working conditions and settings in terms of noise levels were assessed for 100 workers in 13 CGS, in Amman-Jordan as a case study. Noise exposure measurements were performed on site, and action values were calculated and compared with local and international standards. Results showed that workers working continuously for prolonged periods are at greater risk of being exposed to noise levels exceeding the upper action values. The mean average of personal noise exposure for workers at CGS was 86 dB(A); ranging from 82 to 89 dB(A). Communication difficulties, annoyance, low productivity, feeling fatigue, impatience, and complains of loss of hearing were registered. Reverberation Time (RT) was measured in each CGS; Relationship between the RT, noise ambient and space properties ‘‘interior finishing materials” was detected. In conclusion, results from this study demonstrate that health and safety risks resulting from prolonged exposure to noise from coffee grinding machines is an urgent mater that requires further investigations. Setting rules and regulations as well as introducing new laws and regulations are highly recommended as preventive measures against negative health and safety issues associated with this profession. Ó 2019 Elsevier Ltd. All rights reserved.
1. Introduction Noise can be identified as unwanted sound it is a physical hazard and environmental risk that is threatening the health of inhabitants and leading to diseases in the population. The environmental noise is a harmful sound created by human activities, such as transportation noise generated from roads, railways and air traffic, and noise originating from industrial plants (European Union [8]), while the occupational noise is defined as any unwanted sound being produced in working environments (World Health Organization [44], Several previous studies have demonstrated that increased exposure to high levels of noise leads to various health and safety related consequences [42] and [16]. In recent years, many studies have emerged in order to prevent people for being impacted by noise. Constant exposure to noise leads to health issues such as sleep disturbance (Muzet [36,22] annoyance [28] and [30], cardiovascular effects [2,3] hearing loss
⇑ Corresponding author. E-mail address: [email protected] (O.A. Al-Arja). https://doi.org/10.1016/j.apacoust.2019.107047 0003-682X/Ó 2019 Elsevier Ltd. All rights reserved.
[25] learning impairment [26,6] hypertension ischemic heart disease [19]. Disturbing the physical and psychological activities, reducing the productivity and performance [7], poor communication and increased chance of accidents [43], are among the many consequences of prolonged noise exposure. Similarly, the National Institute for Occupational Safety and Health (NIOSH) has extensively described such consequences [38]. Furthermore, a recent document published by the World Health Organization (World Health Organization [44], ‘‘Burden of Disease from environmental noise”, has provided evidence-based description of the consequences of environmental noise on health. According to the document, noise is considered as one of the most common physical factors contributing to increased risk of environmental and occupational health hazards in the workplace. Additionally, noise pollution has been ranked as the second among several environmental stressors for its public health impact on a group of European countries [9]. Prevention of noise impact on health includes understanding, even in real time, the noise levels in the area and thus recent application consist of using wireless sensor network for noise monitoring [45] representing a modern and cheap solution to fulfil with the mandatory noise maps and action plans [27]. In outdoor
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environment, acoustic barriers are the most widespread solution to mitigate the noise produced by the main sources: railway traffic [27,5], airports [11,15], industrial plants [13,12,20], and [32]. Recent developments in the field are shifting the attention towards sonic crystals used as acoustic barriers for road traffic noise mitigation [13,14]. Studies conducted on the individual exposures to daytime noise, have reported high variations in different microenvironments and were greatly determined by personal activities and dependent on environmental noise levels [23]. Investigations on occupational noise exposure were also conducted in many different work fields; for example, in dental clinics [46], in which the noise level was moderate, participants were still annoyed by dental noise sources [47]. Noise exposure from wind turbine and the association between long-term exposure to wind turbine noise with Perceptual responses [29] and the incidence of myocardial infarction [4]. Results from a study conducted by a group of Irish researchers [33], have shown that residential exposure to environmental noise at a shipping port was above the night-time guideline limits set by the WHO, and above Irish levels as well. They concluded that the port noise could be a significant environmental stressor. A similar study on occupational noise at ship recycling yard [24] has shown that workers were at increased risk of induced hearing loss resulting from prolonged hazardous noise levels at the workplace. It is now well-established and extensively documented that health hazards and safety issues are associated with excessive exposure to environmental noise pollution, particularly from transportation sources [21,35]. A large-scale research conducted in the EU has shown that the extent of population exposure to noise in the Dublin area, in particular, was considerable, and that the population exposure to noise was worse in the night-time period [34]. Several studies have also revealed that prolonged occupational exposure to noise caused hearing loss in many industrial entities, for example, in [18]; it was observed that approximately 40.4 percent of production workers had a daily noise exposure exceeding the New Zealand National Standard for occupational noise exposure without ear protection equipment. In Industrial countries, iron and steel factories were among the highest noise level workplaces [48]. In developing countries, however, very few studies were conducted on occupational noise levels inside similar factories and industries [39]. Studies on noise levels among workers of the construction sector have also been investigated [10]. Results have shown that daily noise dose exposure among most workers exceeded 100 percent throughout their working day. Another study has also investigated the correlation between personal noise exposure PNE and occupational stress among palm oil mill workers [37]. The results demonstrated that 100 percent of the noise-exposed group (PNE 85 dB (A)) was experiencing stress condition. Another study about occupational noise exposure on tellers working in Toll Plaza was conducted and concluded that the mean continuous equivalent level was 79.2 dB(A) [1]. In Jordan, studies on the importance of environmental noise pollution and its effect on the public health are scarce. In the study which was conducted on workers of olive oil mill [17], demonstrated that the average recorded noise level was 93.7 dB(A) which is higher than the maximum noise limits allowed by the Jordanian Acoustic Code [31]. Coffee is the world’s most widely traded tropical agricultural commodity. In the Arab World, Coffee is a very common drink that is strongly linked to customs and treated with reverence. Coffee is roasted in different levels ranging from light – medium – dark in temperatures ranging between 165° C and 210° C. It is prepared in a variety of scales ranging from mass-market industrial grinding machines running continuously – processing as much as 100 kg/h
– to the small home grinding machine – processing less than 1 kg/h. It is grinded in different types; unrefined and refined. In general, studies on occupational noise exposure in the Arab Region are very few. To the best of our knowledge, no previous studies were conducted to investigate noise exposure to roasting and grinding coffee machines among workers of the CGS and light industries. Coffee Grinding Shops are widespread in the Arab World. Amman for instance, which is the capital of Jordan has 481 CGS (Greater Amman Municipality, 2019) [49], accommodating around 1000 workers, working from 10:00 am to 10:00 pm all week long. Fig. 1 shows the location of the 481 shops around Amman. Most of the shops are located on main streets. This paper demonstrates and further examines the extent of noise exposure for workers in the roasting and grinding departments of coffee shops in AmmanJordan, and compares the values with local and international standards. The investigation is done by identifying levels of noise produced by coffee grinding machines, quantification of noise potential impacts on workers, comparison of measured values with local and international recommended average exposure values. Indoor working conditions and settings in terms of noise levels are assessed for 100 workers in 13 CGS, in Amman-Jordan as a case study. Noise exposure measurements is performed on site, and action values are calculated and compared with local and international standards. In addition to measurements of noise levels in shops, reverberation time is measured in order to connect the level of noise with the space properties in terms of volume and interior finishing materials. A questionnaire is distributed amongst the workers to emphasize the health effects of the occupational noise on the workers in CGS. A. Space Description of the Case Study The same space of CGS is shared by the operators, accountant (casher), supervisors, manager and the client (buyer). Volume and interior finishing material used in the CGS are listed in Table 1. The main shopfront material for all of the shops is made of glass. It is known that glass is considered a reflective material with small absorption coefficient and has poor acoustical insulation properties. Rigid, nonporous surfaces, such as concrete or plastered blockwork, reflect a high proportion of the incident sound energy. Most of the buildings are constructed largely of hard, nonporous materials and structures which allows high reverberant noise levels. Reducing this reverberant noise can be of considerable benefit in reducing workers‘ noise exposure, although workers standing close to noise sources and affected mainly by the direct sound field will not feel this reduction in noise levels. Sound reflecting materials are used so frequently because of their cheap cost and ruggedness. The need to clean surfaces easily is also often a factor, and in the workplaces connected with human consumption products; cleanliness and hygiene are paramount. Porous absorbing materials shed harmful fibers, pores of the sound absorbing materials which give them their sound absorbing properties will become clogged with dust. In hot environments (such as Jordan) they may have a very limited life, while in food handling shops, they are unacceptable for hygiene reasons, and there is a need to protect the porous surface to maintain its sound absorbing properties. To prevent abrasion, a perforated metal facing or a plastic membrane can be incorporated to make a porous absorber suitable for hygienic environments. Such complicated absorbing structures are expensive. Fig. 2 shows different finishing materials used in the interior design of some of the CGS. There are some techniques involved in reducing the level of noise to an acceptable level to persons in the vicinity; enclosing the noise source as completely as possible, or creating enclosure around the noise source and absorbing the
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Fig. 1. Location of CGS around Amman-Jordan (Greater Amman Municipality, 2019).
Table 1 Interior finishing materials used in CGS, volumes and measured Reverberation Time. Coffee Grinding Shop
A B C D E F G H I J K L M
Volume, m3
342 208 33 138 216 136 87 188 325 307 204 230 92
Volume/Surface area ratio
0.87 0.81 0.59 0.78 0.84 0.75 0.62 0.84 0.93 0.96 0.82 0.85 0.81
Reverberation Time, s
2.46 1.6 0.7 1.04 2.02 1.7 0.67 0.86 2.37 2.4 1.2 1.55 0.9
Materials used in interior design Walls
Floor
Ceiling
M M and W M W PG P W W GB and W PG P PG W
M M M T M T M M PO M T T M
P P and W P P GB P P W and P GB P P P Wand P
W: Wood, P: Plastering, M: Marble, GB: Gypsum Boards, T: Terrazzo, PG: Plexiglas, PO: Porcelain.
noise within it. For effective use of sound absorption; it is known that the same area of sound absorption is more effective when concentrated around the main noise sources [41]. of architectural layouts of CGS in Amman- Jordan are shown in Fig. 3. B. Coffee Grinding Procedure and Description Each shop produces around 100 kg of grinded coffee a day to sellout to local retail shops and supermarkets. This process requires constant exposure to noise generated from grinding this amount by coffee grinding machines, resulting in dangerous noise exposure, in addition to occupational noise exposure caused by individual sales, where demand varies depending on the time of the day, day of the week and season. In addition to the number of coffee grinding machines working at the same time, the existing number of machines ranges between two and eight machines. Although the duration of noise generated from a machine and the number of operated machines were affected by the demand on coffee purchase, information about normal work cycle was
collected by both; interviewing the managers as well as direct observations. According to the interviews with shop managers; the following is considered (1) two machines are operated together for as long as two hours daily, (2) four machines are operated together for four and a half hours, and (3) eight machines are operated together for one and half hour. This is assumed to be constant for all shops. It was noticed that the noise coming from grinding different roasting levels for the coffee grains also varies and for that the noise generated while grinding the different roasted coffee grains is documented.
2. Instrumentation Sound Pressure Level (SPL) meter is used to conduct Area noise measurements. The following are the specifications of the acoustical support devices (XL2 Acoustic Analyzer, SNo. A2A-14419-E0, FW4.03, NTi Audio M2230, SNo. 7492, DS3 Dodecahedron Speaker, PA3 Power Amplifier, calibrator 94/114 dB SPL, Class 1). The sound
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Wall: M, Floor: M, Ceiling: P, counter: W
Wall: W, Floor: M, Ceiling: Wand P, counter: W
Glass shopfront
Wall: PG, Floor: PO, Ceiling: PG, counter: M
Wall: M, Floor: M, Ceiling: P, counter: M
Wall: GB, Floor: M, Ceiling: P, counter: W
Fig. 2. Different finishing materials used in the interior and exterior design of some of the CGS.
characteristics; large volumes of space increase the reverberation time and ambient noise, while decreasing speech intelligibility. To assess the levels of noise exposure in the studied CGS, measurements were taken at the shops at different times during the day, while different grinding machines were operated together. Such procedure helps in determining the extent of time exposure in order to find out whether or not it is above the recommended levels set by the World Health Organization [44]. B. Measurements
Fig. 3. Architectural Layouts for Coffee grinding Shop.
level meter and acoustic calibrator used are tested and calibrated by the Royal Science Society in Amman-Jordan.
3. Methodology A. Overview Levels of workplace noise were measured in (13) CGS, average number of workers per shop is 8 workers. The workers’ personal noise exposure doses and the 8-hour time-weighted average noise levels were also calculated. A self-reported questionnaire was used to assess the impact of noise exposure on communication difficulties, annoyance, reduced productivity, anger, impatience, feeling fatigue, lack of motivation and focus, and finally complaints of loss of hearing caused by workplace noise exposure.The workers were requested to fill out the questionnaire to document the impact of noise on their health. The surveyed CGS mostly use the same grinding machine with one main difference among the shops which was the finishing materials used in the interior design of each shop; (marble, wood, steel and glass, etc.), volume and area of the grinding shop. Space volume, shape and size are of vital importance on the acoustical
Noise of coffee grinding machines could be stated by the weight A dB(A) which is defined in Local and International Standards. For noise emissions, the sound measurement is the sound pressure level at the operator‘s position. A total of 130 measurements were conducted. The instrument was calibrated before and after each measurement according to manufacturer instructions. All measurements were taken during stable and normal working conditions. This ensures the representation of the average working day in regards to working and operational hours, and the volume of production. Workers at the CGS usually stand approximately 0.5–1.0 m away from the sound source; coffee grinding machines. Sound level meter was placed at a height of 1.5 m from the floor and area measurement points were placed (0.5–1.0) meter from the noise sound source horizontally, Fig. 4 shows some of the photos taken during the measurements of the noise sound levels and Reverberation Time inside some of the CGS examined. To ensure uniformity of data collection from various grinding shops, the duration of each measurement was 3 min, and Aweighted equivalent noise levels (LA;eq180s=10 ) were recorded. Time and date of all measurements were recorded as well. 4. Equivalent continuous sound pressure level (LA;eq ) a) LA;eq . during operating grinding machines Measurements of the equivalent continuous sound pressure level, LA;eq , dB(A) were taken for number of the operated machines; i.e. LA;eq for 180 s while two machines were operated together after which another measurement was taken for 180 s when four
O.A. Al-Arja, T.S. Awadallah / Applied Acoustics 158 (2020) 107047
5
Fig. 4. Photos during the measurements of the noise sound levels and Reverberation Time inside some of the studied CGS.
machines were operated together, and so for eight machines. LA;eq was taken at different times during the working day and different days of the week. The time and date of the noise level values were recorded at the shops when workers and customers were both present. b) LA;eq . generated from grinding different types of roasted coffee It was noted that the sound pressure levels vary while grinding the different types of roasted coffee. Measurements were taken when operating one machine while grinding one roasted coffee type of the four different coffee roasting levels; Green, light, medium and dark roasted grains to compare the generated noise. To perform the comparison shop (I) and shop (M) were chosen to conduct measurements of the equivalent continuous sound pressure level LA;eq . c) LA;eq . and the use of different finishing materials It was noted that the level of noise is different in CGS which have different volumes and interior finishing materials; for that it was decided to take more measurements in two of the CGS which have different interior finishing materials; reflective vs absorptive interior finishing materials. CGS (I and M) were taken to explore the effect of interior finishing materials on the level of noise generated from the coffee grinding machines. The interior finishing materials for shop (I) are reflective and semi absorptive materials, while the finishing materials for shop (M) are absorptive materials. Comparison will be performed while operating one machine for the same type of roasted coffee.
5. Evaluation and comparison In Jordan, the noise level of occupational exposure limit (OEL) is 85 dB(A) for an 8-h time-weighted average, which is also used by NIOSH for compliance. This level is equal to the Recommended Exposure Limit of noise from the National Institute for
Occupational Safety and Health (NIOSH), United States [38]. A peak noise level of 135 dB(C) was used as the lower action value that is also used by the European Union (EU) and the UK for the peak sound pressure European [8]. Permissible Exposure Limits (PELs) are introduced by the Occupational Safety and Health Administration (OSHA). PEL of a particular hazard constitutes the acceptable level that an employee can be exposed to during a given workday. To determine if an employee has been exposed above the PEL; OSHA requires analyzing the data by applying an eight-hour time weighted average calculation (TWA) to the collected data. According to the Jordanian Acoustic Code [31], equation (1) can be used to determine the percent dose for a day with different sound levels
D ¼ 100
X Cn Tn
ð1Þ
where D – The percentage dose Cn – The actual hours at a certain sound level Tn – The allowable time for that sound level Allowable noise exposure time Tn in minutes which is calculated using the equation (2):
T n ¼ 480=2ðLp 85Þ
ð2Þ
where Lp is A-weighted sound pressure level in dB(A). In [40] the assessment of workplace noise exposure is done by means of a quantity called the personal daily dose, LEP;d . A weighting is used for workplace noise assessment, LEP;d is in practice always measured using A weighting, and can be written LAEP;d . In Physical Agents (Noise) Directive [8], LAEP;d is known as LEX;8hours . Eq. (3) is for calculating LEP;d , from information about the noise exposure levels during sub-periods:
1 LEP;d ¼ 10 log ðt 1 10L1 =10 þ t 2 10L2 =10 þ Þ T
ð3Þ
where L1 and L2 are the sound pressure levels during the two sub periods, t 1 and t 2 are the time periods for which these levels are maintained, and Tis the overall time period. T must equal the sum
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of t 1 and t2 , the actual time T has been replaced by a standard working day of 8 h. Moreover, the sum of t 1 , t 2 , and t n should equal to 8 working hours, t 1 , t 2 , andt n and T must all be measured in the same units, whether it is hours, minutes or seconds, as shown in Eq. (4).
Fig. 6 shows Personal daily dose in comparison with OEL of 85 dB(A) for all 13 shops. In addition, Fig. 7 shows the percentage daily noise dose (D) at CGS.
1 LEX;8hours ¼ 10 log ðt1 10L1 =10 þ t2 10L2 =10 þ þ tn 10Ln =10 Þ 8 ð4Þ
b) Noise levels – grinding different roasting levels of coffee grains Results The noise level generated from grinding different Roasted coffee grains is different, this depends on the degree of the roasting done to the coffee grains (green, light, medium and dark). Table 3 shows comparison between the LA;eq , dB(A) for grinding of different coffee roasted levels in shops (I and M). Figs. 8 and 9 illustrate the differences in grinding noise levels between Green Grains (GG), Light Roasted Grains (LRG), Medium Roasted Grains (MRG) and Dark Roasted Grains (DRG), for shops (I) and (M), respectively. The noise level generated from grinding the refined medium roasted coffee and the unrefined medium roasted coffee grains varies; the difference between the two cases depends on using different drums in the grinding machines. Figs. 10 and 11 illustrate the noise levels generated from grinding the refined and the un-refined Medium Roasted Coffee Grains. In Shop labeled with (M);LA;eq , for refined coffee grains is 73.7 dB(A), while the, for un-refined coffee grains is 87.7 dB(A). In Shop labeled with (I)
6. Results a) Noise exposure levels - Personal noise exposure Results The workers in all of the CGS were exposed to an average noise LEX;8hours of 86 dB(A); ranging between (82–89) dB(A), according to Table 2. Evaluating by referring to the Jordanian acoustic code [31], it was found that about 70 percent of the results of all measurements were above the OEL of 85 dB(A). Workers do not use any personal hearing protective devices. It is noticed that the noise exposure in shops A, E, F, I, J, and L was higher than the allowable personal noise exposure of 85 dB(A). Fig. 5 shows the Occupational Noise Level (LA;eq ) at CGS when two, four and eight machines are operated simultaneously, respectively.
Table 2 Noise levels, Personal Daily Dose (LEX;8hours .) – A weighting, equivalent continuous noise Levels (LA;eq )* Coffee Grinding Shop
Volume, m3
Personal Daily Dose A weighting LEX;8hours
LA;eq
LCPK max
LAF max
LAF min
Daily Noise Dose, D%
A* B C D E* F* G H I* J* K* L* M
342 208 33 138 216 136 87 188 325 307 204 230 92
86.06 83.06 84.26 83.26 86.26 86.26 84.79 85.86 87.06 88.93 88.88 87.06 82.12
85.7 82.5 84.0 83.0 86.0 86.0 84.4 85.6 86.8 89.0 88.7 86.8 82.4
108.7 98.7 102.6 91.1 104.2 108.8 103.1 103.8 109.6 112.5 108.2 111.3 103.1
91.0 85.4 90.1 81.2 88.6 90.4 88.3 91.6 94.4 97.2 92.6 94.0 90.9
64.6 60.0 52.0 78.5 83.7 57.4 71.9 54.7 65.1 83.8 85.4 81.2 58.4
133.8 71.7 87.8 71.7 133.9 133.6 109.6 133.6 174.8 246.5 261.0 166.1 71.7
* Shops with results above the OEL of 85 dB (A). LCPK max : Peak Sound Pressure Level, C weighted. LAF max : Sound Pressure Level, A weighted Fast Maximum. LAF min : Sound Pressure Level, A weighted Fast Minimum.
Equivalent Sound Pressure Level , dB(A)
Occupaonal Noise Level (LAeq) at Coffee Grinding Shops with different number of operated machines 95.0 90.0 85.0 80.0
8 operated machines
75.0
4 operated machines
70.0
2 operated machines
65.0 60.0 A
B
C
D
E
F
G
H
I
J
K
L
M
Fig. 5. Occupational Noise Level LA;eq at CGS when Two, Four, Eight machines are operated simultaneously, respectively.
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Personal Daily Dose (LEX, 8 hours) at Coffee Grinding Shops 90
Equivalent Sound Pressure Level, dB(A)
88 86 84 82 80 78 A
B
C
D
E
F
G
H
I
J
K
L
M
Fig. 6. Personal daily dose in comparison with OEL of 85 dB(A).
Daily Noise Dose (D) Percentage at Coffee Grinding Shops 300
Daily Noise Dose (D) , %
250 200 150 100 50 A
B
C
D
E
F
G
H
I
J
K
L
M
Fig. 7. Percentage of Daily Noise Dose (D) at CGS.
Table 3 Equivalent continuous sound pressure level LA;eq dB(A) for noise generated from grinding different coffee roasted levels in Shops (I and M). Coffee Roasting Levels
Green Grains (GG) Light Roasted Grains (LRG) Medium Roasted Grains (MRG) Dark Roasted Grains (DRG)
LA;eq , dB(A) Shop (I)
Shop (M)
86.9 86.9 80.0 79.2
88.6 80.1 79.7 79.3
LA;eq , for refined coffee grains is 80.1 dB(A), while the LA;eq , for un-refined coffee grains is 86.8 dB(A). Note that this noise is only for one operated machine. c) Noise levels - Usage of different finishing materials Using of sound reflective materials such as Plexiglas and marble on the walls in addition to high volume values increase the built up noise in the shops. On the contrary, using the absorptive materials
such as wood on interior walls and furniture decrease the built up noise and consequently lower the values of Personal Daily Dose this explains the noise levels in shops D, G, H and M. d) Noise levels – Streets in front of CGS An important follow up of the study is to evaluate the present Noise levels in streets in front of the studied Shops Fig. 12. Four different sites which are connected to the studied grinding coffee shops were selected and the noise levels were measured. Noise sources are from cars and busses passing through the measured sites, in addition to horn soundings from both cars and busses which generate a considerable noise levels at all measured sites. The four main measurement locations were established in front of studied CGS. Measurement equipment installed 1 m from the edge of the street. Site # 1 is in front of Shop (B), Site # 2 is in front of Shop (G), Site # 3 is in front of Shop (H) and Site # 4 is in front of Shop (M), Table 4. Site # 1 is located on a Primary Street within residential area. Site # 2 is located on primary Commercial Street within commercial district. Site # 3 is located on Secondary Street within a
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Equivalent Sound Pressure Leve , dB(A)
Comparison Between Sound Levels of Grinding for Different Roasted Coffee Grains 100 90 80 70 60 50 40 30 20 10 0
Frequency, Hz
16
32
63
125
250
500
1K
2K
4K
8K
16K
GG
8.2
30.1
36.1
50.1
64.3
LRG
12.5
33.8
37.6
56.6
66.3
78.4
82
85.8
78.6
75.4
64.3
73.3
74.4
73.6
67.9
63.6
MRG
6.8
32
35.5
56.9
50.6
65.9
71
74
76.2
71.3
67.4
55.2
DRG
8.6
31.3
35.9
51.9
62.6
69.2
74.9
75.9
69.2
66.3
51.9
Fig. 8. Comparison between sound levels of grinding of different roasted coffee grains in the Shop (I).
Equivalent Sound Pressure Level, dB(A)
Comparison Between Sound Levels of Grinding for Different Roasted Coffee Grains 90 80 70 60 50 40 30 20 10 0
FREQUENCY, HZ
16
32
63
125
250
500
1K
2K
4K
8K
16K
GG
19
28
43
54
69
71
77
79
84
80
68
LRG
12
26
42
53
69
71
77
80
83
80
72
MRG
10
28
40
55
67
70
72
73
75
72
60
DRG
16
28
42
56
64
67
71
72
74
74
62
Fig. 9. Comparison between noise levels of grinding of different roasted coffee grains in the Shop (M).
condensed commercial area sited within residential district. Site # 4 is located on intersection of Primary and Secondary Street within a residential district. For the four sites, a series of four attended one-hour observed noise measurements were performed at all selected measurement sites. Two of the measurements were performed during daytime hours (7:00 am to 7:00 pm), one of the measurements was performed during evening hours (7:00 pm to 10:00 pm). The sound level meter was set up to save and record the measure noise levels each second LA;eq , LA;max and LA;min . An observer was situated with the sound level meter during each measurement period.
Noise levels measured at Sites during the daytime and evening ranged from 67.0 to 75.5 dB(A). The maximum noise level measured during the daytime and evening ranged from 72.0 to 103.0 dB(A). 7. Discussion Applying the limit action values in the Physical agents (noise) Directive (European Union [8]) Table 5, about 30 percent of the studied CGS are exposed to lower exposure action value, 15 percent of CGS are exposed to upper noise exposure action value, 55 percent of CGS are exposed to noise exposure limit value.
9
Equivalent Sound Pressure Level, dB(A)
O.A. Al-Arja, T.S. Awadallah / Applied Acoustics 158 (2020) 107047
Comparison Between Sound Levels of Grinding of Unrefined and Refined Medium Roasted Coffee Grains 90 80 70 60 50 40 30 20 10 0
Frequency, Hz 16
32
63
125
250
500
1K
2K
4K
8K
16K
RMRG
10.2
27.9
40.2
55.3
66.5
69.7
72.4
72.8
75.3
71.8
59.7
UMRG
8.6
31.4
38.1
57.3
67.1
79.2
82.9
84
76.9
72.1
57.9
Equivalent Sound Pressure Level, dB(A)
Fig. 10. Comparison between sound levels of grinding the Refined Medium Roasted Coffee Grains (RMRG) and Un-Refined one (UMRG) in the Shop (M).
Comparison Between Sound Levels of Grinding of Unrefined and Refined Medium Roasted Coffee Grains 90 80 70 60 50 40 30 20 10 0
Frequency, Hz 16
32
63
125
250
500
1K
2K
4K
8K
RMRG
6.8
32
35.5
56.9
65.9
71
74
76.2
71.3
67.4
UMRG
13.6
31.2
41.2
53.3
69.6
72.8
77.8
79.4
83.1
79.3
Fig. 11. Comparison between sound levels of grinding the Refined Medium Roasted Coffee Grains (RMRG) and Un-Refined one (UMRG) in the Shop (I).
Fig. 12. Photos during the measurements of the street noise at different selected sites and different times near the studied CGS.
A number of factors might have caused variance in some measurements such as daily production, demand volume, and changes in type of roasted coffee grains specifications.
At this level of exposure, the employer has a duty to reduce, so far as is reasonably practicable by means other than the use of hearing protection, it is desirable to reduce noise levels in a work-
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Table 4 Equivalent continuous sound pressure level LA;eq , dB(A)) for noise generated in streets in front of the studied Shops. Site number
Date
Time
LA;eq
LAF max
LAF min
Site # 1
19.06.2019 19.06.2019 190.6.2019 190.6.2019 19.06.2019 19.06.2019 20.06.2019 19.06.2019 18.06.2019 20.06.2019 19.06.2019 18.06.2019
10:00–11:00 15:30–16:30 21:00–22:00 8:45–9:45 14:15–15:15 20:45–21:45 12:30–13:30 17:00–18:00 21:0–22:00 11:00–12:00 12:00–13:00 19:30–20:30
73.6 70.8 73.9 73.0 70.3 70.9 69.0 66.9 68.3 71.9 73.2 75.5
89.3 96.2 90.7 101.0 91.8 91.8 72.0 100.9 91.5 96.3 102.8 85.8
60.3 60.1 57.6 62.4 57.1 60.9 56.1 56.4 55.2 61.3 62.0 68.1
Site # 2
Site # 3
Site # 4
Table 5 Exposure action and limit values under the Physical Agents (Noise) Directive [8]. Exposure
LAEP;d
LCpeak
Lower exposure action value Upper exposure action value Exposure limit value
80 dB 85 dB 87 dB
135 dB or 112 Pa 137 dB or 140 Pa 140 dB or 200 Pa
place, that this may improve efficiency if employees can communicate more easily with each other and with clients requirements. Separation between the selling spaces from the grinding machines space can reduce noise levels associated with the noise exposure levels. Consequently, application of absorptive acoustical materials on interior façades is proven to be adopted as an action to reduce noise from grinding machines. Furthermore, noise reduction effects of interior treatments in CGS and coffee production facilities are not recorded or seriously studied, and none has been conducted in the region. Accordingly, the choice of interior finishing materials is apparently done according to aesthetics and visual sense. Using sound pressure level area measurements is an effective method to indicate workers’ noise exposure and occupational noise threats, compared with measurements using the personal dosimeter, were the latter is difficult to conduct, consumes time, and is relatively more expensive. Even though area measurements may underestimate the actual noise exposure amongst workers, the measured noise levels are useful to improve interior design in regards to noise control, surface applications and decisions; consequently, an acoustically enhanced indoor working environment. Noise inside shops could result in significant speech communication interference making it difficult for salespersons and customers to hear one another. The personal dosimeter measurements can be conducted in future research in order to provide more detailed data in regards to occupational noise exposure, and to further develop accurate methods of noise reduction in the workplace. Results from this study strongly recommend establishing noise control measures to include hearing conservation programs with compulsory periodic noise monitoring. CGS included in this study are likely to represent all other CGS not only in Jordan but in the Arab Region in general, as for most of CGS have similar characteristics; unstudied usage of interior finishing materials, grinding machines, workers and customers present in the same space, etc. Due to these aspects, it is likely that the findings of this research can be generalized to CGS in Jordan and the region. 8. Conclusion Results from this study report for the first time on the status and analyze the occupational noise exposure amongst workers in
CGS. Results have demonstrated that workers were exposed to noise level exceeding the OEL of 85 dB(A), and that workers of the studied CGS have all expressed the impact of noise exposure in terms of fatigue, reduced productivity, anger, lack of motivation and focus. This confirms that noise exposure has the potential to be a substantial health concern unless certain noise control measures are implemented. The relationship between the interior finishing materials with the level of built up noise induced by the coffee grinding machines is noticeable and noise can be mitigated by the proper selection of the finishing materials. Although official regulations and acoustical codes exist in Jordan [31], there is an urgent need to develop enforcement methodologies and apply monitoring and inspection protocols to ensure the implementation of these legislations. Strategies of noise assessment and control have been tackled in this paper and may help improve the work environment. Acknowledgments The authors highly acknowledge the financial support of the Deanship of Scientific Research at the German Jordanian University, Jordan under research grant number 1/SABE/2018. In addition, the authors are grateful to the management in the CGS involved in this study for hosting the study and allowing the researchers to do the study. Appendix A. Supplementary data Supplementary data to this article can be found online at https://doi.org/10.1016/j.apacoust.2019.107047. References [1] S. Azmi, S. Dawal, T. Ya, H. Saidin, Occupational Noise Exposure among Toll Tellers at Toll Plaza in Malaysia, in AIP Conference Proceedings 1285, pp. 409, 2010. doi: 10.1063/1.3510565. [2] Babisch W et al. Traffic Noise and Risk of Myocardial Infarction. Epidemiology 2005;16(1):33–40. https://doi.org/10.1097/01.ede.0000147104.84424.24. [3] Bluhm GEC. Cardiovascular effects of environmental noise: Research in Sweden. Noise Health 2011;13:212–6. , http://www.noiseandhealth.org/text. asp?2011/13/52/212/80152. [4] Bräuner EV et al. Long-term wind turbine noise exposure and incidence of myocardial infarction in the Danish nurse cohort. Environ. Int.Pergamon 2018;121:794–802. https://doi.org/10.1016/J.ENVINT.2018.10.011. [5] Bunn F, Paulo ZHT. Assessment of railway noise in an urban setting. Acoustics, Appl. 2016;104:16–23. https://doi.org/10.1016/j.apacoust.2015.10.025. [6] M. Chetoni et al. Global noise score indicator for classroom evaluation of acoustic performances in LIFE GIOCONDA project. pp. 157–171, 2016. doi: 10.1515/noise-2016-0012. [7] Errett J et al. Effects of Noise on Productivity: Does Performance Decrease over Time?”, in Building Integration Solutions. Reston, VA: American Society of Civil Engineers; 2006. p. 1–8. doi: 10.1061/40798(190)18. [8] Union European. Directive 2002/49/EC relating to the assessment and management of environmental noise (END). Off. J. Europ. Commun. 2002; L189:12–25. https://doi.org/10.2779/171432.
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Assessment of occupational noise exposure in coffee grinding shops Omaimah Ali Al-Arja ⇑, Tala Samir Awadallah Department of Architecture and Interior Architecture, School of Architecture and Built Environment, German Jordanian University, Muath Bin Jabal Street, Jabal Amman, Amman, Jordan
a r t i c l e
i n f o
Article history: Received 12 April 2019 Received in revised form 13 September 2019 Accepted 17 September 2019
Keywords: Sound pressure levels Occupational noise exposure measurements Coffee grinding noise
a b s t r a c t This study investigates noise exposure for workers in coffee grinding shops CGS in the Arab Region. The investigation is conducted by identifying the levels of noise produced by coffee grinding machines, quantification of noise potential impacts on workers, comparison of measured values with local and international recommended average exposure values, and setting recommendations for better indoor working environment. Indoor working conditions and settings in terms of noise levels were assessed for 100 workers in 13 CGS, in Amman-Jordan as a case study. Noise exposure measurements were performed on site, and action values were calculated and compared with local and international standards. Results showed that workers working continuously for prolonged periods are at greater risk of being exposed to noise levels exceeding the upper action values. The mean average of personal noise exposure for workers at CGS was 86 dB(A); ranging from 82 to 89 dB(A). Communication difficulties, annoyance, low productivity, feeling fatigue, impatience, and complains of loss of hearing were registered. Reverberation Time (RT) was measured in each CGS; Relationship between the RT, noise ambient and space properties ‘‘interior finishing materials” was detected. In conclusion, results from this study demonstrate that health and safety risks resulting from prolonged exposure to noise from coffee grinding machines is an urgent mater that requires further investigations. Setting rules and regulations as well as introducing new laws and regulations are highly recommended as preventive measures against negative health and safety issues associated with this profession. Ó 2019 Elsevier Ltd. All rights reserved.
1. Introduction Noise can be identified as unwanted sound it is a physical hazard and environmental risk that is threatening the health of inhabitants and leading to diseases in the population. The environmental noise is a harmful sound created by human activities, such as transportation noise generated from roads, railways and air traffic, and noise originating from industrial plants (European Union [8]), while the occupational noise is defined as any unwanted sound being produced in working environments (World Health Organization [44], Several previous studies have demonstrated that increased exposure to high levels of noise leads to various health and safety related consequences [42] and [16]. In recent years, many studies have emerged in order to prevent people for being impacted by noise. Constant exposure to noise leads to health issues such as sleep disturbance (Muzet [36,22] annoyance [28] and [30], cardiovascular effects [2,3] hearing loss
⇑ Corresponding author. E-mail address: [email protected] (O.A. Al-Arja). https://doi.org/10.1016/j.apacoust.2019.107047 0003-682X/Ó 2019 Elsevier Ltd. All rights reserved.
[25] learning impairment [26,6] hypertension ischemic heart disease [19]. Disturbing the physical and psychological activities, reducing the productivity and performance [7], poor communication and increased chance of accidents [43], are among the many consequences of prolonged noise exposure. Similarly, the National Institute for Occupational Safety and Health (NIOSH) has extensively described such consequences [38]. Furthermore, a recent document published by the World Health Organization (World Health Organization [44], ‘‘Burden of Disease from environmental noise”, has provided evidence-based description of the consequences of environmental noise on health. According to the document, noise is considered as one of the most common physical factors contributing to increased risk of environmental and occupational health hazards in the workplace. Additionally, noise pollution has been ranked as the second among several environmental stressors for its public health impact on a group of European countries [9]. Prevention of noise impact on health includes understanding, even in real time, the noise levels in the area and thus recent application consist of using wireless sensor network for noise monitoring [45] representing a modern and cheap solution to fulfil with the mandatory noise maps and action plans [27]. In outdoor
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environment, acoustic barriers are the most widespread solution to mitigate the noise produced by the main sources: railway traffic [27,5], airports [11,15], industrial plants [13,12,20], and [32]. Recent developments in the field are shifting the attention towards sonic crystals used as acoustic barriers for road traffic noise mitigation [13,14]. Studies conducted on the individual exposures to daytime noise, have reported high variations in different microenvironments and were greatly determined by personal activities and dependent on environmental noise levels [23]. Investigations on occupational noise exposure were also conducted in many different work fields; for example, in dental clinics [46], in which the noise level was moderate, participants were still annoyed by dental noise sources [47]. Noise exposure from wind turbine and the association between long-term exposure to wind turbine noise with Perceptual responses [29] and the incidence of myocardial infarction [4]. Results from a study conducted by a group of Irish researchers [33], have shown that residential exposure to environmental noise at a shipping port was above the night-time guideline limits set by the WHO, and above Irish levels as well. They concluded that the port noise could be a significant environmental stressor. A similar study on occupational noise at ship recycling yard [24] has shown that workers were at increased risk of induced hearing loss resulting from prolonged hazardous noise levels at the workplace. It is now well-established and extensively documented that health hazards and safety issues are associated with excessive exposure to environmental noise pollution, particularly from transportation sources [21,35]. A large-scale research conducted in the EU has shown that the extent of population exposure to noise in the Dublin area, in particular, was considerable, and that the population exposure to noise was worse in the night-time period [34]. Several studies have also revealed that prolonged occupational exposure to noise caused hearing loss in many industrial entities, for example, in [18]; it was observed that approximately 40.4 percent of production workers had a daily noise exposure exceeding the New Zealand National Standard for occupational noise exposure without ear protection equipment. In Industrial countries, iron and steel factories were among the highest noise level workplaces [48]. In developing countries, however, very few studies were conducted on occupational noise levels inside similar factories and industries [39]. Studies on noise levels among workers of the construction sector have also been investigated [10]. Results have shown that daily noise dose exposure among most workers exceeded 100 percent throughout their working day. Another study has also investigated the correlation between personal noise exposure PNE and occupational stress among palm oil mill workers [37]. The results demonstrated that 100 percent of the noise-exposed group (PNE 85 dB (A)) was experiencing stress condition. Another study about occupational noise exposure on tellers working in Toll Plaza was conducted and concluded that the mean continuous equivalent level was 79.2 dB(A) [1]. In Jordan, studies on the importance of environmental noise pollution and its effect on the public health are scarce. In the study which was conducted on workers of olive oil mill [17], demonstrated that the average recorded noise level was 93.7 dB(A) which is higher than the maximum noise limits allowed by the Jordanian Acoustic Code [31]. Coffee is the world’s most widely traded tropical agricultural commodity. In the Arab World, Coffee is a very common drink that is strongly linked to customs and treated with reverence. Coffee is roasted in different levels ranging from light – medium – dark in temperatures ranging between 165° C and 210° C. It is prepared in a variety of scales ranging from mass-market industrial grinding machines running continuously – processing as much as 100 kg/h
– to the small home grinding machine – processing less than 1 kg/h. It is grinded in different types; unrefined and refined. In general, studies on occupational noise exposure in the Arab Region are very few. To the best of our knowledge, no previous studies were conducted to investigate noise exposure to roasting and grinding coffee machines among workers of the CGS and light industries. Coffee Grinding Shops are widespread in the Arab World. Amman for instance, which is the capital of Jordan has 481 CGS (Greater Amman Municipality, 2019) [49], accommodating around 1000 workers, working from 10:00 am to 10:00 pm all week long. Fig. 1 shows the location of the 481 shops around Amman. Most of the shops are located on main streets. This paper demonstrates and further examines the extent of noise exposure for workers in the roasting and grinding departments of coffee shops in AmmanJordan, and compares the values with local and international standards. The investigation is done by identifying levels of noise produced by coffee grinding machines, quantification of noise potential impacts on workers, comparison of measured values with local and international recommended average exposure values. Indoor working conditions and settings in terms of noise levels are assessed for 100 workers in 13 CGS, in Amman-Jordan as a case study. Noise exposure measurements is performed on site, and action values are calculated and compared with local and international standards. In addition to measurements of noise levels in shops, reverberation time is measured in order to connect the level of noise with the space properties in terms of volume and interior finishing materials. A questionnaire is distributed amongst the workers to emphasize the health effects of the occupational noise on the workers in CGS. A. Space Description of the Case Study The same space of CGS is shared by the operators, accountant (casher), supervisors, manager and the client (buyer). Volume and interior finishing material used in the CGS are listed in Table 1. The main shopfront material for all of the shops is made of glass. It is known that glass is considered a reflective material with small absorption coefficient and has poor acoustical insulation properties. Rigid, nonporous surfaces, such as concrete or plastered blockwork, reflect a high proportion of the incident sound energy. Most of the buildings are constructed largely of hard, nonporous materials and structures which allows high reverberant noise levels. Reducing this reverberant noise can be of considerable benefit in reducing workers‘ noise exposure, although workers standing close to noise sources and affected mainly by the direct sound field will not feel this reduction in noise levels. Sound reflecting materials are used so frequently because of their cheap cost and ruggedness. The need to clean surfaces easily is also often a factor, and in the workplaces connected with human consumption products; cleanliness and hygiene are paramount. Porous absorbing materials shed harmful fibers, pores of the sound absorbing materials which give them their sound absorbing properties will become clogged with dust. In hot environments (such as Jordan) they may have a very limited life, while in food handling shops, they are unacceptable for hygiene reasons, and there is a need to protect the porous surface to maintain its sound absorbing properties. To prevent abrasion, a perforated metal facing or a plastic membrane can be incorporated to make a porous absorber suitable for hygienic environments. Such complicated absorbing structures are expensive. Fig. 2 shows different finishing materials used in the interior design of some of the CGS. There are some techniques involved in reducing the level of noise to an acceptable level to persons in the vicinity; enclosing the noise source as completely as possible, or creating enclosure around the noise source and absorbing the
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Fig. 1. Location of CGS around Amman-Jordan (Greater Amman Municipality, 2019).
Table 1 Interior finishing materials used in CGS, volumes and measured Reverberation Time. Coffee Grinding Shop
A B C D E F G H I J K L M
Volume, m3
342 208 33 138 216 136 87 188 325 307 204 230 92
Volume/Surface area ratio
0.87 0.81 0.59 0.78 0.84 0.75 0.62 0.84 0.93 0.96 0.82 0.85 0.81
Reverberation Time, s
2.46 1.6 0.7 1.04 2.02 1.7 0.67 0.86 2.37 2.4 1.2 1.55 0.9
Materials used in interior design Walls
Floor
Ceiling
M M and W M W PG P W W GB and W PG P PG W
M M M T M T M M PO M T T M
P P and W P P GB P P W and P GB P P P Wand P
W: Wood, P: Plastering, M: Marble, GB: Gypsum Boards, T: Terrazzo, PG: Plexiglas, PO: Porcelain.
noise within it. For effective use of sound absorption; it is known that the same area of sound absorption is more effective when concentrated around the main noise sources [41]. of architectural layouts of CGS in Amman- Jordan are shown in Fig. 3. B. Coffee Grinding Procedure and Description Each shop produces around 100 kg of grinded coffee a day to sellout to local retail shops and supermarkets. This process requires constant exposure to noise generated from grinding this amount by coffee grinding machines, resulting in dangerous noise exposure, in addition to occupational noise exposure caused by individual sales, where demand varies depending on the time of the day, day of the week and season. In addition to the number of coffee grinding machines working at the same time, the existing number of machines ranges between two and eight machines. Although the duration of noise generated from a machine and the number of operated machines were affected by the demand on coffee purchase, information about normal work cycle was
collected by both; interviewing the managers as well as direct observations. According to the interviews with shop managers; the following is considered (1) two machines are operated together for as long as two hours daily, (2) four machines are operated together for four and a half hours, and (3) eight machines are operated together for one and half hour. This is assumed to be constant for all shops. It was noticed that the noise coming from grinding different roasting levels for the coffee grains also varies and for that the noise generated while grinding the different roasted coffee grains is documented.
2. Instrumentation Sound Pressure Level (SPL) meter is used to conduct Area noise measurements. The following are the specifications of the acoustical support devices (XL2 Acoustic Analyzer, SNo. A2A-14419-E0, FW4.03, NTi Audio M2230, SNo. 7492, DS3 Dodecahedron Speaker, PA3 Power Amplifier, calibrator 94/114 dB SPL, Class 1). The sound
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Wall: M, Floor: M, Ceiling: P, counter: W
Wall: W, Floor: M, Ceiling: Wand P, counter: W
Glass shopfront
Wall: PG, Floor: PO, Ceiling: PG, counter: M
Wall: M, Floor: M, Ceiling: P, counter: M
Wall: GB, Floor: M, Ceiling: P, counter: W
Fig. 2. Different finishing materials used in the interior and exterior design of some of the CGS.
characteristics; large volumes of space increase the reverberation time and ambient noise, while decreasing speech intelligibility. To assess the levels of noise exposure in the studied CGS, measurements were taken at the shops at different times during the day, while different grinding machines were operated together. Such procedure helps in determining the extent of time exposure in order to find out whether or not it is above the recommended levels set by the World Health Organization [44]. B. Measurements
Fig. 3. Architectural Layouts for Coffee grinding Shop.
level meter and acoustic calibrator used are tested and calibrated by the Royal Science Society in Amman-Jordan.
3. Methodology A. Overview Levels of workplace noise were measured in (13) CGS, average number of workers per shop is 8 workers. The workers’ personal noise exposure doses and the 8-hour time-weighted average noise levels were also calculated. A self-reported questionnaire was used to assess the impact of noise exposure on communication difficulties, annoyance, reduced productivity, anger, impatience, feeling fatigue, lack of motivation and focus, and finally complaints of loss of hearing caused by workplace noise exposure.The workers were requested to fill out the questionnaire to document the impact of noise on their health. The surveyed CGS mostly use the same grinding machine with one main difference among the shops which was the finishing materials used in the interior design of each shop; (marble, wood, steel and glass, etc.), volume and area of the grinding shop. Space volume, shape and size are of vital importance on the acoustical
Noise of coffee grinding machines could be stated by the weight A dB(A) which is defined in Local and International Standards. For noise emissions, the sound measurement is the sound pressure level at the operator‘s position. A total of 130 measurements were conducted. The instrument was calibrated before and after each measurement according to manufacturer instructions. All measurements were taken during stable and normal working conditions. This ensures the representation of the average working day in regards to working and operational hours, and the volume of production. Workers at the CGS usually stand approximately 0.5–1.0 m away from the sound source; coffee grinding machines. Sound level meter was placed at a height of 1.5 m from the floor and area measurement points were placed (0.5–1.0) meter from the noise sound source horizontally, Fig. 4 shows some of the photos taken during the measurements of the noise sound levels and Reverberation Time inside some of the CGS examined. To ensure uniformity of data collection from various grinding shops, the duration of each measurement was 3 min, and Aweighted equivalent noise levels (LA;eq180s=10 ) were recorded. Time and date of all measurements were recorded as well. 4. Equivalent continuous sound pressure level (LA;eq ) a) LA;eq . during operating grinding machines Measurements of the equivalent continuous sound pressure level, LA;eq , dB(A) were taken for number of the operated machines; i.e. LA;eq for 180 s while two machines were operated together after which another measurement was taken for 180 s when four
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Fig. 4. Photos during the measurements of the noise sound levels and Reverberation Time inside some of the studied CGS.
machines were operated together, and so for eight machines. LA;eq was taken at different times during the working day and different days of the week. The time and date of the noise level values were recorded at the shops when workers and customers were both present. b) LA;eq . generated from grinding different types of roasted coffee It was noted that the sound pressure levels vary while grinding the different types of roasted coffee. Measurements were taken when operating one machine while grinding one roasted coffee type of the four different coffee roasting levels; Green, light, medium and dark roasted grains to compare the generated noise. To perform the comparison shop (I) and shop (M) were chosen to conduct measurements of the equivalent continuous sound pressure level LA;eq . c) LA;eq . and the use of different finishing materials It was noted that the level of noise is different in CGS which have different volumes and interior finishing materials; for that it was decided to take more measurements in two of the CGS which have different interior finishing materials; reflective vs absorptive interior finishing materials. CGS (I and M) were taken to explore the effect of interior finishing materials on the level of noise generated from the coffee grinding machines. The interior finishing materials for shop (I) are reflective and semi absorptive materials, while the finishing materials for shop (M) are absorptive materials. Comparison will be performed while operating one machine for the same type of roasted coffee.
5. Evaluation and comparison In Jordan, the noise level of occupational exposure limit (OEL) is 85 dB(A) for an 8-h time-weighted average, which is also used by NIOSH for compliance. This level is equal to the Recommended Exposure Limit of noise from the National Institute for
Occupational Safety and Health (NIOSH), United States [38]. A peak noise level of 135 dB(C) was used as the lower action value that is also used by the European Union (EU) and the UK for the peak sound pressure European [8]. Permissible Exposure Limits (PELs) are introduced by the Occupational Safety and Health Administration (OSHA). PEL of a particular hazard constitutes the acceptable level that an employee can be exposed to during a given workday. To determine if an employee has been exposed above the PEL; OSHA requires analyzing the data by applying an eight-hour time weighted average calculation (TWA) to the collected data. According to the Jordanian Acoustic Code [31], equation (1) can be used to determine the percent dose for a day with different sound levels
D ¼ 100
X Cn Tn
ð1Þ
where D – The percentage dose Cn – The actual hours at a certain sound level Tn – The allowable time for that sound level Allowable noise exposure time Tn in minutes which is calculated using the equation (2):
T n ¼ 480=2ðLp 85Þ
ð2Þ
where Lp is A-weighted sound pressure level in dB(A). In [40] the assessment of workplace noise exposure is done by means of a quantity called the personal daily dose, LEP;d . A weighting is used for workplace noise assessment, LEP;d is in practice always measured using A weighting, and can be written LAEP;d . In Physical Agents (Noise) Directive [8], LAEP;d is known as LEX;8hours . Eq. (3) is for calculating LEP;d , from information about the noise exposure levels during sub-periods:
1 LEP;d ¼ 10 log ðt 1 10L1 =10 þ t 2 10L2 =10 þ Þ T
ð3Þ
where L1 and L2 are the sound pressure levels during the two sub periods, t 1 and t 2 are the time periods for which these levels are maintained, and Tis the overall time period. T must equal the sum
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of t 1 and t2 , the actual time T has been replaced by a standard working day of 8 h. Moreover, the sum of t 1 , t 2 , and t n should equal to 8 working hours, t 1 , t 2 , andt n and T must all be measured in the same units, whether it is hours, minutes or seconds, as shown in Eq. (4).
Fig. 6 shows Personal daily dose in comparison with OEL of 85 dB(A) for all 13 shops. In addition, Fig. 7 shows the percentage daily noise dose (D) at CGS.
1 LEX;8hours ¼ 10 log ðt1 10L1 =10 þ t2 10L2 =10 þ þ tn 10Ln =10 Þ 8 ð4Þ
b) Noise levels – grinding different roasting levels of coffee grains Results The noise level generated from grinding different Roasted coffee grains is different, this depends on the degree of the roasting done to the coffee grains (green, light, medium and dark). Table 3 shows comparison between the LA;eq , dB(A) for grinding of different coffee roasted levels in shops (I and M). Figs. 8 and 9 illustrate the differences in grinding noise levels between Green Grains (GG), Light Roasted Grains (LRG), Medium Roasted Grains (MRG) and Dark Roasted Grains (DRG), for shops (I) and (M), respectively. The noise level generated from grinding the refined medium roasted coffee and the unrefined medium roasted coffee grains varies; the difference between the two cases depends on using different drums in the grinding machines. Figs. 10 and 11 illustrate the noise levels generated from grinding the refined and the un-refined Medium Roasted Coffee Grains. In Shop labeled with (M);LA;eq , for refined coffee grains is 73.7 dB(A), while the, for un-refined coffee grains is 87.7 dB(A). In Shop labeled with (I)
6. Results a) Noise exposure levels - Personal noise exposure Results The workers in all of the CGS were exposed to an average noise LEX;8hours of 86 dB(A); ranging between (82–89) dB(A), according to Table 2. Evaluating by referring to the Jordanian acoustic code [31], it was found that about 70 percent of the results of all measurements were above the OEL of 85 dB(A). Workers do not use any personal hearing protective devices. It is noticed that the noise exposure in shops A, E, F, I, J, and L was higher than the allowable personal noise exposure of 85 dB(A). Fig. 5 shows the Occupational Noise Level (LA;eq ) at CGS when two, four and eight machines are operated simultaneously, respectively.
Table 2 Noise levels, Personal Daily Dose (LEX;8hours .) – A weighting, equivalent continuous noise Levels (LA;eq )* Coffee Grinding Shop
Volume, m3
Personal Daily Dose A weighting LEX;8hours
LA;eq
LCPK max
LAF max
LAF min
Daily Noise Dose, D%
A* B C D E* F* G H I* J* K* L* M
342 208 33 138 216 136 87 188 325 307 204 230 92
86.06 83.06 84.26 83.26 86.26 86.26 84.79 85.86 87.06 88.93 88.88 87.06 82.12
85.7 82.5 84.0 83.0 86.0 86.0 84.4 85.6 86.8 89.0 88.7 86.8 82.4
108.7 98.7 102.6 91.1 104.2 108.8 103.1 103.8 109.6 112.5 108.2 111.3 103.1
91.0 85.4 90.1 81.2 88.6 90.4 88.3 91.6 94.4 97.2 92.6 94.0 90.9
64.6 60.0 52.0 78.5 83.7 57.4 71.9 54.7 65.1 83.8 85.4 81.2 58.4
133.8 71.7 87.8 71.7 133.9 133.6 109.6 133.6 174.8 246.5 261.0 166.1 71.7
* Shops with results above the OEL of 85 dB (A). LCPK max : Peak Sound Pressure Level, C weighted. LAF max : Sound Pressure Level, A weighted Fast Maximum. LAF min : Sound Pressure Level, A weighted Fast Minimum.
Equivalent Sound Pressure Level , dB(A)
Occupaonal Noise Level (LAeq) at Coffee Grinding Shops with different number of operated machines 95.0 90.0 85.0 80.0
8 operated machines
75.0
4 operated machines
70.0
2 operated machines
65.0 60.0 A
B
C
D
E
F
G
H
I
J
K
L
M
Fig. 5. Occupational Noise Level LA;eq at CGS when Two, Four, Eight machines are operated simultaneously, respectively.
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Personal Daily Dose (LEX, 8 hours) at Coffee Grinding Shops 90
Equivalent Sound Pressure Level, dB(A)
88 86 84 82 80 78 A
B
C
D
E
F
G
H
I
J
K
L
M
Fig. 6. Personal daily dose in comparison with OEL of 85 dB(A).
Daily Noise Dose (D) Percentage at Coffee Grinding Shops 300
Daily Noise Dose (D) , %
250 200 150 100 50 A
B
C
D
E
F
G
H
I
J
K
L
M
Fig. 7. Percentage of Daily Noise Dose (D) at CGS.
Table 3 Equivalent continuous sound pressure level LA;eq dB(A) for noise generated from grinding different coffee roasted levels in Shops (I and M). Coffee Roasting Levels
Green Grains (GG) Light Roasted Grains (LRG) Medium Roasted Grains (MRG) Dark Roasted Grains (DRG)
LA;eq , dB(A) Shop (I)
Shop (M)
86.9 86.9 80.0 79.2
88.6 80.1 79.7 79.3
LA;eq , for refined coffee grains is 80.1 dB(A), while the LA;eq , for un-refined coffee grains is 86.8 dB(A). Note that this noise is only for one operated machine. c) Noise levels - Usage of different finishing materials Using of sound reflective materials such as Plexiglas and marble on the walls in addition to high volume values increase the built up noise in the shops. On the contrary, using the absorptive materials
such as wood on interior walls and furniture decrease the built up noise and consequently lower the values of Personal Daily Dose this explains the noise levels in shops D, G, H and M. d) Noise levels – Streets in front of CGS An important follow up of the study is to evaluate the present Noise levels in streets in front of the studied Shops Fig. 12. Four different sites which are connected to the studied grinding coffee shops were selected and the noise levels were measured. Noise sources are from cars and busses passing through the measured sites, in addition to horn soundings from both cars and busses which generate a considerable noise levels at all measured sites. The four main measurement locations were established in front of studied CGS. Measurement equipment installed 1 m from the edge of the street. Site # 1 is in front of Shop (B), Site # 2 is in front of Shop (G), Site # 3 is in front of Shop (H) and Site # 4 is in front of Shop (M), Table 4. Site # 1 is located on a Primary Street within residential area. Site # 2 is located on primary Commercial Street within commercial district. Site # 3 is located on Secondary Street within a
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Equivalent Sound Pressure Leve , dB(A)
Comparison Between Sound Levels of Grinding for Different Roasted Coffee Grains 100 90 80 70 60 50 40 30 20 10 0
Frequency, Hz
16
32
63
125
250
500
1K
2K
4K
8K
16K
GG
8.2
30.1
36.1
50.1
64.3
LRG
12.5
33.8
37.6
56.6
66.3
78.4
82
85.8
78.6
75.4
64.3
73.3
74.4
73.6
67.9
63.6
MRG
6.8
32
35.5
56.9
50.6
65.9
71
74
76.2
71.3
67.4
55.2
DRG
8.6
31.3
35.9
51.9
62.6
69.2
74.9
75.9
69.2
66.3
51.9
Fig. 8. Comparison between sound levels of grinding of different roasted coffee grains in the Shop (I).
Equivalent Sound Pressure Level, dB(A)
Comparison Between Sound Levels of Grinding for Different Roasted Coffee Grains 90 80 70 60 50 40 30 20 10 0
FREQUENCY, HZ
16
32
63
125
250
500
1K
2K
4K
8K
16K
GG
19
28
43
54
69
71
77
79
84
80
68
LRG
12
26
42
53
69
71
77
80
83
80
72
MRG
10
28
40
55
67
70
72
73
75
72
60
DRG
16
28
42
56
64
67
71
72
74
74
62
Fig. 9. Comparison between noise levels of grinding of different roasted coffee grains in the Shop (M).
condensed commercial area sited within residential district. Site # 4 is located on intersection of Primary and Secondary Street within a residential district. For the four sites, a series of four attended one-hour observed noise measurements were performed at all selected measurement sites. Two of the measurements were performed during daytime hours (7:00 am to 7:00 pm), one of the measurements was performed during evening hours (7:00 pm to 10:00 pm). The sound level meter was set up to save and record the measure noise levels each second LA;eq , LA;max and LA;min . An observer was situated with the sound level meter during each measurement period.
Noise levels measured at Sites during the daytime and evening ranged from 67.0 to 75.5 dB(A). The maximum noise level measured during the daytime and evening ranged from 72.0 to 103.0 dB(A). 7. Discussion Applying the limit action values in the Physical agents (noise) Directive (European Union [8]) Table 5, about 30 percent of the studied CGS are exposed to lower exposure action value, 15 percent of CGS are exposed to upper noise exposure action value, 55 percent of CGS are exposed to noise exposure limit value.
9
Equivalent Sound Pressure Level, dB(A)
O.A. Al-Arja, T.S. Awadallah / Applied Acoustics 158 (2020) 107047
Comparison Between Sound Levels of Grinding of Unrefined and Refined Medium Roasted Coffee Grains 90 80 70 60 50 40 30 20 10 0
Frequency, Hz 16
32
63
125
250
500
1K
2K
4K
8K
16K
RMRG
10.2
27.9
40.2
55.3
66.5
69.7
72.4
72.8
75.3
71.8
59.7
UMRG
8.6
31.4
38.1
57.3
67.1
79.2
82.9
84
76.9
72.1
57.9
Equivalent Sound Pressure Level, dB(A)
Fig. 10. Comparison between sound levels of grinding the Refined Medium Roasted Coffee Grains (RMRG) and Un-Refined one (UMRG) in the Shop (M).
Comparison Between Sound Levels of Grinding of Unrefined and Refined Medium Roasted Coffee Grains 90 80 70 60 50 40 30 20 10 0
Frequency, Hz 16
32
63
125
250
500
1K
2K
4K
8K
RMRG
6.8
32
35.5
56.9
65.9
71
74
76.2
71.3
67.4
UMRG
13.6
31.2
41.2
53.3
69.6
72.8
77.8
79.4
83.1
79.3
Fig. 11. Comparison between sound levels of grinding the Refined Medium Roasted Coffee Grains (RMRG) and Un-Refined one (UMRG) in the Shop (I).
Fig. 12. Photos during the measurements of the street noise at different selected sites and different times near the studied CGS.
A number of factors might have caused variance in some measurements such as daily production, demand volume, and changes in type of roasted coffee grains specifications.
At this level of exposure, the employer has a duty to reduce, so far as is reasonably practicable by means other than the use of hearing protection, it is desirable to reduce noise levels in a work-
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Table 4 Equivalent continuous sound pressure level LA;eq , dB(A)) for noise generated in streets in front of the studied Shops. Site number
Date
Time
LA;eq
LAF max
LAF min
Site # 1
19.06.2019 19.06.2019 190.6.2019 190.6.2019 19.06.2019 19.06.2019 20.06.2019 19.06.2019 18.06.2019 20.06.2019 19.06.2019 18.06.2019
10:00–11:00 15:30–16:30 21:00–22:00 8:45–9:45 14:15–15:15 20:45–21:45 12:30–13:30 17:00–18:00 21:0–22:00 11:00–12:00 12:00–13:00 19:30–20:30
73.6 70.8 73.9 73.0 70.3 70.9 69.0 66.9 68.3 71.9 73.2 75.5
89.3 96.2 90.7 101.0 91.8 91.8 72.0 100.9 91.5 96.3 102.8 85.8
60.3 60.1 57.6 62.4 57.1 60.9 56.1 56.4 55.2 61.3 62.0 68.1
Site # 2
Site # 3
Site # 4
Table 5 Exposure action and limit values under the Physical Agents (Noise) Directive [8]. Exposure
LAEP;d
LCpeak
Lower exposure action value Upper exposure action value Exposure limit value
80 dB 85 dB 87 dB
135 dB or 112 Pa 137 dB or 140 Pa 140 dB or 200 Pa
place, that this may improve efficiency if employees can communicate more easily with each other and with clients requirements. Separation between the selling spaces from the grinding machines space can reduce noise levels associated with the noise exposure levels. Consequently, application of absorptive acoustical materials on interior façades is proven to be adopted as an action to reduce noise from grinding machines. Furthermore, noise reduction effects of interior treatments in CGS and coffee production facilities are not recorded or seriously studied, and none has been conducted in the region. Accordingly, the choice of interior finishing materials is apparently done according to aesthetics and visual sense. Using sound pressure level area measurements is an effective method to indicate workers’ noise exposure and occupational noise threats, compared with measurements using the personal dosimeter, were the latter is difficult to conduct, consumes time, and is relatively more expensive. Even though area measurements may underestimate the actual noise exposure amongst workers, the measured noise levels are useful to improve interior design in regards to noise control, surface applications and decisions; consequently, an acoustically enhanced indoor working environment. Noise inside shops could result in significant speech communication interference making it difficult for salespersons and customers to hear one another. The personal dosimeter measurements can be conducted in future research in order to provide more detailed data in regards to occupational noise exposure, and to further develop accurate methods of noise reduction in the workplace. Results from this study strongly recommend establishing noise control measures to include hearing conservation programs with compulsory periodic noise monitoring. CGS included in this study are likely to represent all other CGS not only in Jordan but in the Arab Region in general, as for most of CGS have similar characteristics; unstudied usage of interior finishing materials, grinding machines, workers and customers present in the same space, etc. Due to these aspects, it is likely that the findings of this research can be generalized to CGS in Jordan and the region. 8. Conclusion Results from this study report for the first time on the status and analyze the occupational noise exposure amongst workers in
CGS. Results have demonstrated that workers were exposed to noise level exceeding the OEL of 85 dB(A), and that workers of the studied CGS have all expressed the impact of noise exposure in terms of fatigue, reduced productivity, anger, lack of motivation and focus. This confirms that noise exposure has the potential to be a substantial health concern unless certain noise control measures are implemented. The relationship between the interior finishing materials with the level of built up noise induced by the coffee grinding machines is noticeable and noise can be mitigated by the proper selection of the finishing materials. Although official regulations and acoustical codes exist in Jordan [31], there is an urgent need to develop enforcement methodologies and apply monitoring and inspection protocols to ensure the implementation of these legislations. Strategies of noise assessment and control have been tackled in this paper and may help improve the work environment. Acknowledgments The authors highly acknowledge the financial support of the Deanship of Scientific Research at the German Jordanian University, Jordan under research grant number 1/SABE/2018. In addition, the authors are grateful to the management in the CGS involved in this study for hosting the study and allowing the researchers to do the study. Appendix A. Supplementary data Supplementary data to this article can be found online at https://doi.org/10.1016/j.apacoust.2019.107047. References [1] S. Azmi, S. Dawal, T. Ya, H. Saidin, Occupational Noise Exposure among Toll Tellers at Toll Plaza in Malaysia, in AIP Conference Proceedings 1285, pp. 409, 2010. doi: 10.1063/1.3510565. [2] Babisch W et al. Traffic Noise and Risk of Myocardial Infarction. Epidemiology 2005;16(1):33–40. https://doi.org/10.1097/01.ede.0000147104.84424.24. [3] Bluhm GEC. Cardiovascular effects of environmental noise: Research in Sweden. Noise Health 2011;13:212–6. , http://www.noiseandhealth.org/text. asp?2011/13/52/212/80152. [4] Bräuner EV et al. Long-term wind turbine noise exposure and incidence of myocardial infarction in the Danish nurse cohort. Environ. Int.Pergamon 2018;121:794–802. https://doi.org/10.1016/J.ENVINT.2018.10.011. [5] Bunn F, Paulo ZHT. Assessment of railway noise in an urban setting. Acoustics, Appl. 2016;104:16–23. https://doi.org/10.1016/j.apacoust.2015.10.025. [6] M. Chetoni et al. Global noise score indicator for classroom evaluation of acoustic performances in LIFE GIOCONDA project. pp. 157–171, 2016. doi: 10.1515/noise-2016-0012. [7] Errett J et al. Effects of Noise on Productivity: Does Performance Decrease over Time?”, in Building Integration Solutions. Reston, VA: American Society of Civil Engineers; 2006. p. 1–8. doi: 10.1061/40798(190)18. [8] Union European. Directive 2002/49/EC relating to the assessment and management of environmental noise (END). Off. J. Europ. Commun. 2002; L189:12–25. https://doi.org/10.2779/171432.
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