The effect of lean on occupational health and safety and productivity in the garment industry – a literature review

ABSTRACT Introduction: Lean is increasingly used by garment manufacturers to increase productivity for reducing costs and lead time. Yet, it has not been documented in a review whether lean actually improves productivity, and it is an open question whether lean can improve productivity without jeopardizing occupational health and safety (OHS). Objective: This article contributes to this debate by reviewing the present knowledge about the effect of lean on productivity and OHS in the RMG industry. Methodology: A systematic review of the available peer-reviewed studies of lean in RMG and its related effects on productivity and OHS. Results: We identified 18 relevant articles, which showed strong positive effect of lean on productivity and weak positive to mixed effects of lean on OHS. Conclusions: Our results indicate that lean in RMG is likely to improve productivity, but RMG manufacturers need to make careful assessment of the effect of lean on OHS and adjust lean implementation accordingly.


Introduction
The readymade garment (RMG) industry is a labour-intensive low-skilled assembly industry, which has motivated international brands for outsourcing their production to lowwage developing countries in Asia, Africa and South America. Recently, international buyers have shifted a part of their production from China to Bangladesh, Myanmar, Cambodia and Ethiopia, seeking even cheaper labour force. However, the industry has realized that outsourcing to countries with a cheap labour force is far from securing a permanent competitive advantage and the possibility to shift continuously the production to countries with even lower salaries will be exhausted soon. As a consequence, international buyers are increasingly inducing garment manufacturers in developing countries to adopt new manufacturing systems for productivity and quality improvements (Kader & Akter, 2014). A key system for this endeavour is lean manufacturing, which is based on 'The Toyota Production System' or TPS originating in Japan (Liker, 2004;Ohno, 1988;Spear &

Background
RMG is considered as one of the most labour-intensive industries in the world, which motivates RMG industries to locate in countries where labour is available in abundance. China is the largest supplier of RMG to the world followed by other Asian countries such as Bangladesh, India, Sri Lanka, Vietnam, Cambodia and Indonesia. The majority of these countries are clearly identified by cheap labour availability in a growing economy and share common problems, such as lack of trained workers, inefficient midlevel management, low productivity and poor working conditions (Hasnin & Ahsan, 2016;Rakib & Adnan, 2015).
China's RMG industry started back in 1949. In the earlier years, the Chinese RMG industries suffered from low productivity until the economic reforms in 1978. Subsequently, by 2000, the Chinese RMG gained advantage and was able to capture one fifth of the global market share (Zhang, Kong, & Ramu, 2015). Occupational hazards were common in the RMG industry in China and the country started to adopt legislative measures to improve workers safety (Zhang, Wang, & Li, 2010). However, in the last 10 years, the prevailing cost advantage in China became obscure, and in consequence, many garment companies started to exploit opportunities in other growing Asian markets in order to hold down costs and to reduce overdependence on China (Witchell & Symington, 2013).
In this context, Bangladesh has emerged as the biggest gainer from the Chinese industrial shifts and assumed the position of the second largest garment exporter in the world. But in terms of productivity, the performance of the Bangladeshi garment industry is below the mark and buyers point to late delivery as one of the main issues of the industry (Kader & Akter, 2014). In addition, poor OHS conditions are considered among the important reasons for lower productivity in Bangladesh (Berg, Hedrich, Kempf, & Tochtermann, 2011;Nargis, 2013;Saha & Mazumder, 2015). Moreover, the productivity of the garment industry in Bangladesh is lower in comparison not only to China but to other Asian countries as well. In response to low productivity, garment manufacturers in Bangladesh are focusing on productivity improvement of their plants by applying lean tools such as proper line balancing, time study, and housekeeping (Islam & Adnan, 2016).
Furthermore, adherence to social compliance standards is also lower in Bangladesh than in competing regional countries (Baughn, Bodie, & McIntosh, 2007;Maalouf, Hasle, Vang, & Hoque, 2019). Indeed, in addition to the focus on productivity and efficiency, the RMG industry in Bangladesh is striving to improve workplace safety for the millions of garment workers in compliance with the national and international labour standards and labour rights (Ansary & Barua, 2015). Moreover, on the wake of incidents like Rana-plaza and Tazreen fire, pressure from the international buyers and legislators increased dramatically and pushed the garment industry towards stricter compliance with norms and regulations related to workplace safety and workers' rights (Hasnin & Ahsan, 2016;Rahman & Hossain, 2010).
As for other Asian and African countries such as Sri Lanka, India, China, and Jordan, they have also adopted lean manufacturing system in order to meet global business challenges. In this context, available studies revealed benefits and issues of lean implementation on work conditions (Al-Jawazneh, 2011;Chiromo, Nel, & Sebele, 2015;Gamage, Vilasini, Perera, & Wijenatha, 2012;Raju & Mahato, 2014;Taj, 2008).

Lean philosophy and its possible effects on OHS
Lean has a long history from Taylor's scientific management in the early twentieth century to TPS (Liker, 2004). It was adopted by American automakers as an attempt to increase the competitiveness of the American auto industry in the late 1980s (Womack & Jones, 1996;Womack, Jones, & Roos, 1990), and it has today found a wide application in manufacturing and many other industries. Lean manufacturing is a system that greatly influences organizational performance and culture (Pakdil & Leonard, 2015), but it is also a much debated concept without a commonly agreed definition, which varies from a general production philosophy to a list of practical tools (Shah & Ward, 2007). The promises of lean are not always fulfilled (Vest & Gamm, 2009), which is often explained by implementation failures (Sparrow & Otaye-Ebede, 2014). Still, lean system is widely used in both manufacturing and service industries, and even though a deep lean culture is rare to find, many lean tools or bundles of tools are applied in practice. Yet, the effect of lean on the productivity of the garment industry, which is unlike studies of lean in other industries mainly located in developing countries may not be taken for granted. The short experience with manufacturing industry and low qualifications of both managers and workers may enhance the wellknown implementation failures of lean. It is, therefore, pertinent to review the available studies of effects of lean on productivity in the RMG.
A common problem in manufacturing industries surfaces when increases of productivity are achieved at the cost of the health and safety of the workers (Von Thiele Schwarz, Hasson, & Tafvelin, 2016;Westgaard & Winkel, 2011). The reasons for prioritizing productivity over OHS include lack of knowledge, cost of application, and the separation of OHS priorities from core business goals and daily operations. Yet, the same studies show that, when operational improvements are integrated with safety priorities, the overall business performance improves (Abad, Lafuente, & Vilajosana, 2013). While some studies found evidence that lean has a negative effect on OHS (Landsbergis, Cahill, & Schnall, 1999;Stewart et al., 2009), others indicated that there may be both positive and negative effects of lean on OHS (Hasle, 2014). Yet, there are particular good reasons to be aware of the negative effects of lean especially in repetitive assembly work (Brännmark & Håkansson, 2012;Hasle et al., 2012). Indeed, it is well established that repetitive work is a risk factor for the development of repetitive strain injuries (RSI) (Buckle & Jason Devereux, 2002;Muggleton, Allen, & Chappell, 1999). For RMG, it is also convincingly proven the repetitive tasks of sewing machine operators carry a high risk of RSI (Ozturk & Esin, 2011;Sealetsa & Thatcher, 2011;Vezina, Tierney, & Messing, 1992). The question is, therefore, what effects lean may have on the risk of RSI as well as other occupational injuries.

Methodology
The study uses a systematic literature review approach (Grant & Booth, 2009) in order to identify and analyse relevant studies focusing on the relationship between lean implementation and OHS and productivity outcomes in the RMG industry. We followed a standard procedure for the literature search, data extraction, and synthesis as outlined below. The research team was composed of three researchers based in Bangladesh and Denmark. The researchers decided jointly at the start of the study about search terms, definitions and the research questions.
The literature search included empirical studies published in peer-reviewed international journals applying both qualitative, quantitative and mixed-methods articles that focused on the relationship between lean, productivity and OHS in the RMG industry. We started the literature search using the following three strings: String 1: Garment, textile, clothing, apparel, RMG String 2: Lean, value stream mapping, kaizen, 5S String 3: OHS, occupational health and safety, safety, ergonomics, occupational health However, we obtained only two studies that meet the criteria. Then, we decided to include only String 1 and String 2 from three databases: Business Source premier, Scopus, and Web of Science. The strings were used in all databases with appropriate truncations and Boolean operators, such as AND and OR.
The inclusion criteria are: • Articles considering lean implementation in the RMG • English language articles • Peer-reviewed journal and articles that include empirical data • Articles published in the period of 1990-2019 Afterwards, three reviewers independently screened the selected titles and abstracts of the 94 eligible articles. We have excluded articles focusing on topics such as textile machinery, garments product design, chemical barrier, ergonomic clothing comfort, garments trade regulation, and cloths classification (26 articles excluded). Then, the search results from each database were merged and duplicates deleted (11 articles deleted). Afterwards, in the screening phase, we read the whole text and used the following inclusion criteria: articles focusing on the effects of lean implementation on productivity and/or OHS in the RMG sector. We also excluded articles, which have insufficient information about methodology and/or results. We ended up with 14 articles focusing on the effect of lean implementation on productivity and/or OHS.
Then, a crosscheck by Google Scholar and the references and citations of selected articles was performed in order to capture the maximum number of hits. We added four articles originated from the crosscheck of Google Scholar and the citations and references of the selected 14 articles. We finally obtained 18 articles for the systematic review (see Figure 1).
Following recommendations in the literature (Hasle et al., 2012), three researchers assessed the quality of these 18 articles independently according to four classifications: (1) positive association with productivity; (2) negative association with productivity; (3) positive association with OHS; (4) negative association with OHS. For each of the four classifications, we assessed the relationship as 'strong' or 'weak' association.
(1) Strong evidence for a positive (AA) or negative (BB) association: We assessed the effect of lean implementation on OHS and productivity as strongly positive association (or strong negative), if the study uses robust methods including statistical analysis, multiple case study, controlled experiment, and mixed methods.  Table 1 describes the main characteristics of the 18 articles identified by the systematic search. As for the used research methods, 10 articles used survey methods and quantitative analysis. In these 10 articles, the number of participants varied from 100 to 1189 participants, and the number of participating organizations varied from 3 to 31. Seven articles used qualitative methods. Hereof, five used single case studies and two used qualitative interviews involving 8 and 11 garment plants, and finally one single case study employed and experiment at the shopfloor level.

Summary of results
As for the focus of the studies, nine articles explored the whole garment production process from cutting to packaging, one article focused on quality management, and one article reported the results of an experiment in the sewing line. The remaining seven articles focused on selected activities in the factory such as cutting, sewing, finishing, spinning, total productive  -WIP -Worker fatigue maintenance department and different teams like quick response manufacturing (QRM) and progressive bundle system (PBS). As for lean practices, all articles (18) focused on the implementation of different bundles of lean practices, such as 5S, Value Stream Mapping (VSM), Total Quality Management (TQM), Kaizen event, Total Productive Maintenance (TPM), Quick Response Manufacturing (QRM), Single Minute Exchange Die (SMED) and visual management. As for OHS practices, 12 articles reported practices such as worker involvement, participation, 5S, work station design and ergonomics. Table 2 describes the productivity and OHS results and our assessment of the results. Eight articles found strong positive association between lean practices and productivity, while eight articles found weak positive association for the same relationship, and none found a negative association. As for the positive association between lean practices and OHS outcomes, five articles identified strong positive association, while other nine articles found weak positive association for the same relationship. As for the negative association between lean practices and OHS outcomes, one article identified strong negative association, while another article reported a weak negative association for the same relationship. Table 3 presents a summary of distribution of the 18 studies according to the three categories of association.

Relationship between lean implementation and productivity
Table 1 reveals six major themes regarding the relationship between lean and productivity in the reviewed 18 articles. In the next sections, we present the relevant results within each of the six themes.

Production time
The articles focus on Production time, Cut-ship time, Dock-to-Dock time, On-time delivery, and Set-up time. Three studies found strong to weak positive association between lean and Cut-ship time, Dock-to-Dock time, On-time delivery, and one article found weak positive association between lean and Set-up time. For example, Kumar, Mohan, and Mohanasundaram (2019) found significant achievement of reduction cycle time and that is 34% and Wickramasinghe and Wickramasinghe (2011b) found evidence that cut-to-ship ratio increased 4% and 10% in two factories, Dock-to-Dock time reduced by 20 and 43 days in two factories, and On-time delivery ratio increased by 4% in one factory and 30% in another factory. Moreover, same authors report in another article, that dock-to-dock time was reduced by 33 days, cut-to-ship ratio increased 3% (from 96% to 99%), and on-time delivery increased by 4% (Wickramasinghe & Wickramasinghe, 2017). As for Set-up time, one study reports a reduction in one factory from 28 to 8 min (Marudhamuthu, Krishnaswamy, & Pillai, 2011). In another article, the authors (Wickramasinghe & Perera, 2016) found that reduction of defective tools replacement based on TPM had influenced positively on-time delivery.

Efficiency
Seven articles focused on the productivity of workers and line efficiency, and all studies involving productivity of workers and efficiency found strong or weak positive association between lean implementation and efficiency. Three studies show increased efficiency ranging from 12.5% to 90% (Carvalho, Carvalho, & Silva, 2019;Kumar et al., 2019; Marudhamuthu et al., 2011;Quddus & Nazmul Ahsan, 2014;. Less specific results were found in a Sri Lankan garment factory (Wickramasinghe & Perera, 2016) with improvements in the cost-effectiveness, product quality, on-time delivery and volume flexibility. Similarly, a comparison of two groups of lean and non-lean factories found that lean factories were more efficient than non-lean factories (Kaur, Marriya, & Kashyap, 2016).

Quality
Six studies focused on different dimensions of product quality: defects per hundred unit (DHU), zero defect, accepted quality limit (AQL) level, rework rate, and rejection rate. Even though the studies used different methods and approaches to the improvement of quality, they all found improvements. For example, in one article (Quddus & Nazmul Ahsan, 2014), the authors reported 62% reduction in a number of DHU (from 134 to 51 defects) in one of the factories. Vijayakumar and Robinson (2016) found that, after implementing 5S defective garment material reduced from 11.29% to 5.27% and applying same tool another author reported that, rework reduced 75% after 9 months (Ahmed, Islam, & Kibria, 2018). Another researchers found that AQL improved after lean implementation (Wickramasinghe & Wickramasinghe, 2011b, 2017. Moreover, Gamage, Jayamaha, and Grigg (2016) have found evidence that Taguchi's Quality Philosophy and Practice was positively related to lean manufacturing system and had positive effect on manufacturing quality outcomes.

Waste
Reduction of waste (Muda) through VSM is a key element in lean. Six studies identified wastes, such as WIP (work in progress) and inventory level, and considerable improvements could be achieved through VSM. Some studies reported a reduction of WIP ranging from 30% to 89% (Kumar et al., 2019;Kumar & Sampath, 2012;Quddus & Nazmul Ahsan, 2014). In another two articles, the authors reported 152% increase in value-added ratio, associated with the whole production process (from supplier to manufacturer to customer) (Silva, 2012) while Hodge, Goforth Ross, Joines, & Thoney (2011) reported an increase of 105% in value added activities.

Housekeeping
Five articles focused on housekeeping and 5S, and the studies show that applying 5S has several positive effects. For example, one study, Vijayakumar and Robinson (2016) investigated the effect of using 5S for reduction of defects and lead time. The authors reported a decrease in defect rate from 11.3% to 5.3% and a reduction in production Note: a Two articles reported mixed results (both negative and positive association between lean and OHS) in selected 18 articles.
lead time from 81.5 to 74.7 h. In another study, indicate that 5S helps to reduce 54.67 m 2 space in a floor (Ahmed et al., 2018). In others, articles reported an increase in 5S audit score from 1.8 to 3.2 after applying 5S recommendations (Quddus & Nazmul Ahsan, 2014), better utilization of resources in cutting and sewing section (Kumar et al., 2019) and reduce the waste beyond the expectation (Hodge et al., 2011).

Intensity and duration of the adoption of lean practices
Five studies focused on the stages of implementation of lean practices and the tendency is that the longer duration of lean the larger impact. One of the articles found that most companies that adopted lean are in the initial phases of lean implementation (9 out of 10 plants). Only one plant had shown consistent lean implementation with visible results (Kaur et al., 2016). As for the duration of lean implementation, several studies indicated that the duration of the time of lean implementation had positive effects on workers' productivity, employees participation in decision-making, and managerial commitment (Jackson & Mullarkey, 2000;Wickramasinghe & Wickramasinghe, 2011b, 2017. In particular, early adopters of lean had a more established continuous improvement system. Moreover, Hodge et al. (2011) found evidence that a model for lean adoption including bundle of tools such as, VSM, policy deployment, visual management, continuous improvement, standardized work, just in time, is more likely to be successful in the garment industries than the implementation of individual practices.

Relationship between lean implementation and OHS outcomes
Three themes regarding the relationship between lean and OHS can be identified in the 14 articles (Table 1). In the next sections, we present the relevant results within each of the three OHS themes.

Housekeeping
Five articles focused on the impact of 5S on OHS during lean implementation. The studies show a clear tendency of 5S to improve ergonomics conditions especially by reducing unnecessary movements of workers. For example, number of article, the implementation of 5S improved material storage, which reduced unnecessary movements and ergonomic problems of workers (Hodge et al., 2011;Kumar et al., 2019). Moreover, one study observed that shop-floor and machine cleaning had positive effects on the respiratory system and general health of the workers (Quddus & Nazmul Ahsan, 2014). Other studies found that 5S implementation reduced unnecessary movements related to machine and table positions (Vijayakumar & Robinson, 2016) and reduced almost 20% movement in fabric and accessories room (Ahmed et al., 2018), which reduced the reach distance of materials and decreased musculoskeletal disorders and mental strain.

Ergonomics
Four studies focused on the effect of lean on human fatigue and ergonomic practices. The results are mixed with both positive and negative outcomes. Quddus and Nazmul Ahsan (2014) reported improvement in ergonomics as workers experienced a better fit into their workstations. Moreover, studies reported that VSM helped reduce human fatigue and effort by shortening the distance between cutting and production section (Kumar & Sampath, 2012;Marudhamuthu et al., 2011). Yet, one study presented evidence that lean implementation had negative effects on OHS reflected in sitting discomfort, noise and heat (Abeysekera & Illankoon, 2016).

Worker engagement and participation
Five articles focused on the effect of lean on workers engagement and participation and reported both positive and negative associations. For example, one article presented evidence that organizational support during lean implementation increased job involvement, commitment, awareness and reduced turnover intention (Gamage et al., 2016;Kaur et al., 2016;Wickramasinghe & Wickramasinghe, 2011b). Other articles presented evidence showing that lean practices increased workers commitment and participative decision-making (Wickramasinghe & Wickramasinghe, 2011a, 2017, and reduced absenteeism and labour turnover (Jackson & Mullarkey, 2000;Wickramasinghe & Wickramasinghe, 2011b). Moreover, Locke and Romis (2007) found evidence that lean implementation had reduced task complexity and consequently increased employee participation. As for the negative effects of lean, Jackson and Mullarkey (2000) found evidence that lean implementation caused increase of peer pressure and conflicts among team members responsible for lean transformation.

Discussion
Our objective is to investigate the effect of lean implementation on OHS and productivity in the RMG industry. It is known that this industry has witnessed an increased competition especially in the form of shorter delivery time, smaller lots, frequent change of styles, and cost reduction. These developments have put extra pressure on garment manufacturers, which have adopted lean as an important tool to meet this pressure. Our literature review indicates that they do so with good reason. Indeed, all the studies show a positive effect of lean on the overall productivity. The studied garment manufactures have used a wide array of tools focusing on efficiency, waste reduction, change over time and quality, and all the applied tools have proven to have positive effects. Yet our review reveals that most lean initiatives are in the initial phases. Indeed, few factories have reached a high lean maturity level, and in many cases the studied lean initiatives are in the pilot phase, where long-term effects are uncertain, and there may be a risk that the effects may vanish when the initial interest and engagement run out. The review, therefore, indicates that the RMG industry still has a wide scope for gaining productivity improvements from more extensive and in-depth lean implementation. However, it is a subject for further research to what extent this is possible given the cultural context as well as the present managerial capabilities in the RMG industries located in developing countries. Earlier research (Brännmark & Håkansson, 2012;Hasle et al., 2012) indicates that lean tends to have a negative effect on workers' health in manual assembly work which in several ways resembles the sewing tasks in the RMG industry. It could, therefore, be expected that such health risks could also be found as a consequence of lean implementation in the sewing industry. However, contrary to this expectation, our review shows with a few exceptions a trend towards positive effects. The studies have found positive effects of lean on a variety of items such as injuries, accidents, ergonomics, fatigue, teamwork, workers' commitment, turnover rate and absenteeism. Most of these items are referred to as psychosocial factors (absenteeism, turnover intension, job involvement, job satisfaction, and human fatigue). It is interesting that such positive effects are also found in developing countries with a tradition for low workers involvement. It should be noted though that there are also some contradictory results, and it cannot be concluded as such that lean has a positive effect on psychosocial factors. As mentioned above, most of the studied lean cases are in initial phases and these findings may, therefore, be related to involvement of workers in the lean implementation.
As for RSI, it is well established from studies in industrialized countries (Vezina et al., 1992) that sewing carries a risk of long-term RSI. This risk is only included in two studies (Abeysekera & Illankoon, 2016;Marudhamuthu et al., 2011), with a focus on short-term effects and with mixed results. The risk of RSI and MSDs is, therefore, still unexplored, and there may very well be an important risk to consider and therefore a high priority for further studies. It is especially an open question what the long-term effect would be after years of exposure to a lean production set-up in garment.
Although the majority of the studies point towards positive effects, these results must be interpreted with caution. Most studies have weak associations due to methodological limitations such as single case studies and qualitative material. They also focus on shortterm effects, and so far, the knowledge about long-term effects for both physical and psychosocial risks and general working conditions is very limited. However, it is at the same time important to emphasize that if lean had dramatic negative effects, it would probably have appeared in the reviewed studies.
At the same time, as we can conclude that lean tend to have a positive association with OHS and working conditions, it is evident that more research is needed. This is, in particular, the case for the long-term effect on lean on workers' health. Furthermore, more in-depth studies of the effects of various lean tools are needed. It may be for instance that 5S and value stream mapping have positive effects whereas waste removal based on-time and motion studies has more ambiguous effects on OHS. It is, in this context, important to make longitudinal studies with statistical comparison of lean and non-lean production systems.

Conclusion
There are so far still few studies of lean implementation in the RMG industry and its effects on productivity and OHS. But based on the review of the available studies, some preliminary conclusions can be drawn. There is significant evidence for a positive association between lean and productivity on several parameters such as efficiency, value-added time, change over time and quality. The studies are in most cases based on relatively short lean exposure time and it can therefore be expected that there may even be larger benefits to achieve in the long run. Such achievements would require though a more in-depth knowledge about implementation of lean in the RMG industry in a development country context.
For the effects of lean on OHS, the studies are more limited and based on weaker methodologies. Although there are studies showing mixed results, the tendency is clearly positive, and it seems likely that lean can have a positive to neutral effect on OHS in the short term. This effect will of course depend on the context of the implementation. Whereas more studies of the effects of lean on OHS and working conditions are needed, it is, in particular, important to emphasize that there are so far no studies of the long-term effect of lean on OHS, in particular the risk of RSI. It would also be relevant to study the particular effects of the broad range of lean tools on OHS. As for practice, companies will benefit from lean implementation with productivity increases which may give a competitive advantage but focus for the companies should be secure a sustainable lean implementation which is integrating OHS. Management, therefore, needs to make a careful assessment of the possible effects on OHS associated with the different lean tools and practices, and thereby secure that appropriate measures to control the risk are applied. Otherwise, lean implementation can potentially increase the risk of detrimental effects on workers' health.

Disclosure statement
No potential conflict of interest was reported by the authors.

Funding
The work was supported by the DANIDA, Denmark [grant no.14-07AAU]. Earlier version of this paper has been presented in ICMERE 2017, Dhaka, Bangladesh.