The experience of employment strain and activation among temporary agency workers in Canada

ABSTRACT This article integrates the employment strain model with the social stress model in order to reveal the mechanisms that explain the relation between precarious employment and mental well-being. This model is applied to the case of temporary agency employment by analysing 41 in-depth interviews with temporary agency workers from Canada. The results show how temporary agency workers perceive employment-related uncertainties and efforts mainly as negative and to a lesser extent as positive experiences, respectively evoking strain or activation. Further, it is revealed how uncertainties and efforts mutually reinforce each other, which increases strain, and how support can serve as a buffer.


Introduction
In industrialised nations, structural socio-economic changes drastically altered the world of work from the 1970s onwards (Jessop, 1994;Vosko, 2011). In many countries, the introduction of workfare principles and the subsequent neoliberal labour market reforms have led to a declining significance of the standard employment relationship and an expansion of precarious employment (Quinlan, Mayhew, & Bohle, 2001;Standing, 2009Standing, , 2011Virtanen et al., 2005). The standard employment relationship is characterised by full-time permanent employment, an attractive wage, social benefits, training, and regulatory protections. Its counterpartprecarious employmentcan be conceived as a combination of several of the opposite characteristics: employment instability (e.g. temporary employment), low material rewards (e.g. low income, lack of benefits), erosion of workers' rights and social protection, de-standardised working time arrangements (e.g. unpredictable schedules, flexible or irregular working hours), limited training opportunities, lack of employee representation (e.g. trade union representation), and imbalanced interpersonal power relations with employers and colleagues (Kalleberg, Reskin, & Hudson, 2000;Rodgers, 1989;Van Aerden, Moors, Levecque, & Vanroelen, 2014).
Because non-standard employment is growing in Western labour markets, it is important to gain a deeper understanding of its consequences for workers' health and well-being. In the literature, different types of non-standard and precarious employment arrangements, such as temporary (agency) employment, are found to be associated with poorer health and well-being (Benach et al., 2014;De Moortel, Vandenheede, & Vanroelen, 2014;Quinlan et al., 2001;Virtanen et al., 2005). The employment strain model offers an interesting framework to interpret findings of poorer health and well-being among non-standard workers (Lewchuk, Clarke, & de Wolff, 2008). Non-standard employment situations are often related to (potentially) stressful experiences regarding the nature of the employment relationship, namely employment relationship uncertainty (i.e. uncertainty over the terms and conditions of [future] employment) and employment relationship effort (i.e. efforts to remain in employment). Employment relationship support (i.e. support to deal with precarious employment) can serve as a buffer for the negative consequences of these efforts and uncertainties. The analyses of Lewchuk et al. (2008) show that employment strain (defined by Lewchuk et al. [2008] as the combination of high employment relationship uncertainty and high employment relationship effort) is indeed a strong predictor of poor health and well-being, certainly when accompanied by low levels of support. However, some studies report positive or no associations between non-standard and precarious employment arrangements and mental well-being (De Cuyper et al., 2008). Partly, this can be explained by the heterogeneity of atypical employment arrangements (De Cuyper et al., 2008). However, other reasons can also be considered. The employment strain model does not take into account the possibility that non-standard forms of employment are associated with positive experiences and consequently lead to positive mental wellbeing. For example, sometimes non-standard work can be associated with experiences of freedom, flexibility, motivation, and opportunities for learning and acquiring experience. These experiences may in turn be related to positive mental well-being (Bosmans, Hardonk, De Cuyper, & Vanroelen, 2016;De Cuyper et al., 2008). A theoretical understanding of the underlying mechanisms of these positive experiences, which we describe as "activation", can be reached using the social stress framework (Mirowsky & Ross, 1986;Pearlin, 1989;Thoits, 1995). This article proposes a conceptual model for interpreting both negative and positive psychosocial experiences related to employment arrangements that can be objectively described as precarious.
Subsequently, this model is applied to the specific case of temporary agency workers living in the Greater Toronto-Hamilton region in Canada. In Canada (Ontario), the temporary agency sector is hardly regulated. There are no rules regarding the use of temporary agency employment. Temporary agency workers should be paid the minimum wage or more, but an equal-pay regulation in order to guarantee that agency workers earn the same income and benefits than their permanent colleagues is lacking (Workers' Action Centre, 2015). Several arguments justify the choice for temporary agency workers as the target group. First, temporary agency employment is characterised by a non-standard employment relationship with employees performing labour on behalf of a temporary employment agency (the de juro employer, legally responsible for the workers in Canada) for a third party, which is the client-company (the de facto employer). This triadic employment relationship involves higher vulnerability to issues such as withholding mandatory rights, excessive or conflicting demands, and problematic health-and-safety protection (Aletraris, 2010;Underhill & Quinlan, 2011). However, agencies may possibly serve as a form of support as well, for example by providing an excellent service in finding employment for workers (Bosmans et al., 2016;Van Breugel, Van Olffen, & Olie, 2005). Second, temporary agency employment is often considered as precarious because it tends to be related to high job insecurity (Hall, 2006;Silla, Gracia, & Peiro, 2005), low wages and few benefits (Kalleberg et al., 2000), unpredictable or irregular schedules (Aletraris, 2010;Kalleberg et al., 2000), poor training opportunities (Knox, 2010), and higher chances of unfavourable social relations at work (Forde & Slater, 2006;Kirkpatrick & Hoque, 2006;Padavic, 2005). Third, earlier quantitative studies among Canadian workers by Lewchuk, de Wolff, and King (2007) and de Wolff 2008, 2011) illustrate that temporary agency workers experience the highest level of employment strain compared with other groups of workers.
The empirical part of this study serves two aims. First, guided by the conceptual model, it illustrates how temporary agency workers perceive their employment situation in terms of both negative and positive experiences. The qualitative approach enables the focus to be on the lived-through experiences of agency workers concerning employment strain and activation. Second, there is a focus on how employment relationship uncertainties, efforts, and support mutually reinforce each other in shaping workers' experiences. In particular, the study shows how uncertainties and efforts mutually strengthen each other, and consequently increase strain. In addition, the role of employment relationship support as a buffer against employment strain and poor mental well-being is illustrated.

The employment strain model and temporary agency employment
The employment strain model was developed to study the association between precarious employment and health and well-being (Lewchuk, Clarke, & de Wolff, 2011). The components of the model are predominantly assessed from a strain perspective, highlighting the potentially damaging mental wellbeing consequences of stressful employment experiences (see Table 1). As stated above, this is often but not always the case. Below, the components are reviewed in terms of their potential straining effects. Additionally, the next paragraph discussesbased on insights from social stress theoryhow temporary agency employment may lead to activation experiences.
Employment relationship uncertainty concerns uncertainty over the terms and conditions of (future) employment and includes three subcomponents. The first subcomponent is employment fragility, that is, the level of control over future employment and the frequency of renegotiation of employment terms. It assesses contract length, uncertainty over access to future employment, uncertainty about whether current employers will offer more work, insufficient notice to accept work, not receiving a record of pay, not being paid on time, and receiving pay different from the expected. Many studies indicate that temporary agency workers often experience job insecurity (Aletraris, 2010;Hall, 2006;Padavic, 2005) and tend to feel easily replaceable (Knox, 2010). The second subcomponent is earnings uncertainty, that is, the level of control over future earnings. It assesses the inability to plan income in advance and the unavailability of social-security coverage (e.g. disability insurance, pension benefits, paid sick leave). Temporary agency workers are known to suffer from income insecurity (Pedersen, Hansen, & Mahler, 2004) and are often not entitled to disability insurance and pension plans (Aletraris, 2010;Kalleberg et al., 2000;Purser, 2006). The last subcomponent is scheduling uncertainty, that is, control over work schedules. It assesses issues such as insufficient notice to plan ahead one's work and the problematic combination of employment with household responsibilities and social activities (Lewchuk et al., 2011). Although findings are not entirely consistent (Forde & Slater, 2006;Hall, 2006), many studies indicate that temporary agency workers have less regular and more unsocial working times than permanent employees and that their working hours often fluctuate according to labour demands (Aletraris, 2010;Knox, 2010).
Employment relationship effort concerns various efforts to remain in employment. These can be divided into four subcomponents. The first subcomponent is the effort in keeping employed, that is, the constant efforts associated with the search for new employment, the effort of maintaining a job, discrimination at work and in getting work, and obligations towards unpaid training. The constant search for work can be demanding for temporary agency workers: Purser (2006) describes how day labourers have to wait at employment agencies for hours in the hope of securing a day's work. Forde and Slater (2006) mention that temporary agency workers report high levels of anxiety over the threat of arbitrary dismissal, discrimination, and victimisation. The second subcomponent, constant evaluation effort, is the constant need to ensure positive employer assessments in order to secure continuation of employment. Temporary agency workers tend to perform at higher levels (Smith, 1998), skip breaks, accept dangerous tasks, or work through illnesses and injuries (Degiuli & Kollmeyer, 2007), hoping to secure their further employment or to obtain a permanent contract. The evaluation of client-companies can sometimes influence future wages of temporary agency workers (Elcioglu, 2010). The constant need to put your best face on and the competition among temporary agency workers can be very stressful (Pedersen et al., 2004). The third and fourth subcomponents are multiple worksites effort and multiple employer effort, that is, demands from balancing multiple worksites (e.g. working at more than one location, conflicts caused by working at multiple locations, unpaid travel hours, and work in unfamiliar places) and for multiple employers (e.g. changing employers frequently, conflicting demands from multiple employers, and having more than one employer at the same time) (Lewchuk et al., 2011). Having to meet new people in new places all the time can be psychologically demanding (Lewchuk et al., 2011;Pedersen et al., 2004). Moreover, the triadic employment relationship and frequently changing work environments render temporary agency workers more vulnerable to occupational health-and-safety risks (Maceachen et al., 2012).
Employment relationship support concerns various forms of support to deal with uncertainties and efforts. Three subcomponents are distinguished. The first subcomponent is union support. Non-standard jobs often lack union coverage, since shop-stewards' primary concerns often go to regular workers (Byoung-Hoon & Frenkel, 2004;Degiuli & Kollmeyer, 2007;Kalleberg et al., 2000). Temporary workers may even become the target of discrimination by shop-stewards (Byoung-Hoon & Frenkel, 2004). The second subcomponent concerns support received by co-workers, friends, family, and the community. Temporary agency workers tend to experience employment relations with employers and permanent colleagues as more problematic than permanent employees do (Forde & Slater, 2006;Krausz & Brandwein, 1992). They are often not treated as real members of the organisation (Knox, 2010;Padavic, 2005;Rogers, 1995). Support from friends and family is important for coping with work-related problems, but this appears to be lacking more often for precarious workers (Bosmans et al., 2016;Clarke, Lewchuk, de Wolff, & King, 2007;Lewchuk et al., 2007). The final subcomponent is household economic support, which concerns the general economic position of the household (Lewchuk et al., 2011). Temporary agency workers not only tend to have lower wages and less benefits (compared with permanent employees) (Hall, 2006;Kvasnicka & Werwatz, 2003;Purser, 2006), but are also inclined to live together with people in similar precarious employment situations, making the economic support at the household level all the more fragile (Lewchuk et al., 2011). Although each component of the employment strain model can in itself impact health and wellbeing, multiplicative effects are also assumed. The combination of high employment relationship uncertainty and high employment relationship effort has the strongest association with poor health and wellbeing outcomes (Lewchuk et al., 2008). Lewchuk et al. (2008) also revealed that high levels of support can buffer the negative impact of precarious employment on mental well-being.
Employment strain and activation: the social stress perspective on precarious employment Empirical applications of the employment strain model clearly show that employment relationship uncertainty and employment relationship effort negatively affect mental well-being (Lewchuk et al., 2008). However, the employment strain model does not give an explanation for positive psychological experiences related to temporary (agency) employment. Temporary (agency) employment can also be associated with experiences of freedom, flexibility, motivation, and opportunities for learning and acquiring experience (Bosmans et al., 2016;De Cuyper et al., 2008;Guest, 2004). Variety, free choice over when and where to work, not being bound by long-term commitment, and better work-life balance are mentioned as potential advantages of temporary (agency) work (Guest, 2004). In addition, the idea of temporary employment as a steppingstone to more permanent employment is highlighted in the literature (Bosmans et al., 2016;De Cuyper et al., 2008;Guest, 2004;Virtanen et al., 2005). Further, temporary employment can be part of an alternative lifestyle, wherein periods of employment are alternated with travelling or other (creative) activities (Bosmans et al., 2016). Another example is reflected in highly skilled knowledge workers who may deliberately pursue a boundaryless career (Guest, 2004). In these examples, the features of temporary (agency) employment may have positive effects on workers' mental well-being (Bosmans et al., 2016;De Cuyper et al., 2008).
At this point, the social stress model (Pearlin, 1989;Thoits, 1995) may help to clarify both negative and positive mechanisms shaping the relation between precarious employment and mental wellbeing (in contrast to the employment strain model that only considers negative consequences). A social stress approach shows how stressors related to employment situations can give rise to strain and may consequently negatively affect mental wellbeing (as suggested in the employment strain model), but also how stressors can activate individuals with potentially positive consequences for their mental well-being (Bosmans et al., 2016;Pearlin, 1989;Thoits, 1995). Strain often follows from an imbalance between demanding exposures (stressors) and coping resources, which help to deal with these stressors or offer control over the (work) environment. Activation, in turn, occurs when individuals feel that they have sufficient coping resources. It is a positive experience in which stressors evoke challenges, motivation, and (learning) opportunities in workers (Bosmans et al., 2016;De Witte, Verhofstadt, & Omey, 2007). Coping resources are personal or social characteristics upon which people may draw when dealing with stressors. Examples of personal coping resources are a sense of control/mastery of life, self-esteem, Type A personality, hardiness, and invulnerability. Persons characterised by the opposite personal characteristics (e.g. powerlessness, fatalism, low self-esteem) will have more difficulties coping with stressors (Pearlin, 1989;Thoits, 1995). Social coping resources (i.e. employment relationship support) refer to instrumental, informational, and/or emotional support from relevant others such as family members, friends, or co-workers (Thoits, 1995). These coping resources may affect the choice and the efficacy of the coping styles and strategies that people use in response to stressors (Pearlin, 1989;Thoits, 1995). Coping styles are general habitual preferences for approaching problems (e.g. withdraw or approach, deny or confront, become active or remain passive) (Thoits, 1995). Coping strategies, a related concept to coping styles, are behavioural or cognitive endeavours to manage stressors (Thoits, 1995). They can be problem focused (e.g. actively advocating for a contract renewal) or emotion focused (e.g. attributing being unemployed to labour market conditions rather than to one's own limitations) (Miller & Major, 2000;Thoits, 1995). Most coping strategies are adaptive, that is, they reduce levels of stress, but there are also maladaptive coping strategies that maintain or increase levels of stress, for example self-blame or alcohol abuse (Brown, Westbrook, & Challagalla, 2005). Moreover, some coping strategies may also become stressors themselves. For example, when constantly searching for work as a coping strategy becomes a very intensive daily preoccupation, it can become a stressor (an employment relationship effort). This could certainly affect mental well-being when the results/rewards (e.g. finding a good job) are unsatisfactory compared with the efforts made. Thus, whether precarious employment influences mental well-being also depends on the rewards individuals receive in response to their efforts (Siegrist, 1996). Finally, other factors such as personal and social characteristics (e.g. skill level, family composition, age, gender, ethnicity), personal preferences and expectations (e.g. volition in case of temporary contracts), and former experiences might also be important moderators in the relation between precarious employment and mental well-being. Although the focus of this study is mainly on uncertainties, efforts, and support, these other factors will also emerge from the results.
Integrating the three components of the employment strain model (employment relationship uncertainty, effort, and support) in the more general social stress approach results in the Employment Strain/ Activation (ESA) model presented in Figure 1. This model, which is developed in the current article, shows thatas assumed by the employment strain modelprecarious employment is related to employment relationship uncertainties and efforts. However, these uncertainties and efforts can either result in strain or they can activate workers, which is consistent with social stress theory. In other words, the objective employment characteristics (e.g. temporary contract, flexible working times, multiple employers) are equally present for all workers in the same employment situation, but these features can evoke either negative feelings such as powerlessness and frustration (strain) or feelings of motivation and challenge (activation). Therefore, in contrast to the employment strain model, the ESA model defines strain as only one potential outcome of uncertainties and efforts. How temporary agency workers experience their employment situation and whether strain or activation occurs depends on the coping mechanisms available to workers (e.g. employment relationship support), personal and social characteristics, personal preferences and expectations, former experiences, and rewards. For example, earnings uncertainty alone does not necessarily lead to strain, but rather it is the combination of different forms of negatively perceived uncertainties and efforts and a lack of rewards and adaptive coping mechanisms that lead to strain.

Methods
Forty-one interviews with temporary agency workers were used for this study. The sample consisted of men (n = 20) and women (n = 21) from a range of ethnic backgrounds (white, Afro-American, Metis, Latin American, South Asian, Southeast Asian, Chinese, and Filipino) who worked in a large number of different sectors. The interviewees had varying occupations such as administrative worker, manufacturing worker, ICT consultant, translator, teacher, lab technician, telemarketer, waiter, note taker, homecare worker, web designer, and so on. The age of the interviewees varied between 22 and 65 years. The interviews were drawn from two related projects.
The first pool of interviews was collected in 2006 (for further information, see Clarke et al., 2007;Lewchuk et al., 2011) as a follow-up on a survey of 3244 employees living in Toronto and nearby communities. A number of the respondents who were in less permanent employment and/or reported high levels of employment strain in the quantitative survey were selected for an interview approximately six months after the survey. Of these, the interviews with temporary agency workers (n = 14) were retained for this study. Interviewees were defined as temporary agency workers when temporary agency employment was their main source of income during the last three months before the interview.
The second pool of interviews was drawn from a case study about precarity and its impact on household and community well-being, which was part of a larger project called "Poverty and Employment Precarity in Southern Ontario" (PEPSO) (Lewchuk et al., 2013). This project included a survey of Figure 1. The Employment Strain/Activation model. workers in the Greater Toronto-Hamilton area and 83 interviews with individuals in different forms of precarious employment conducted between the fall of 2010 and late 2011. The interviews with temporary agency workers (n = 27; based on their own description) were included in this study. Several methods were used to recruit participants in the PEPSO project. Temporary agency workers were addressed via advertisements in newspapers, postings on Kijiji and Craiglist websites, recruitment through PEPSO community partners, and the Progressive Moulded Products (PMP) Action Centre (an organisation that was set up by former PMP workers after 2000 workers lost their jobs in 2008 following the sudden bankruptcy of the company) (Lewchuk et al., 2013).
The interviews were semi-structured and open-ended in nature. Each interview was about one hour in length. In both pools, the topic list consisted of questions that explored a range of issues related to the employment relationship, the employment history of the interviewee, work-related health and well-being, and the worker's household and community engagement.
The interviews were coded by the first author, using the employment strain model as a guiding interpretation framework (Lewchuk et al., 2011). Codes at different levels were applied. For example, "employment relationship uncertainty" is a level 1 code and is the overarching coding level of "earnings uncertainty" (level 2) and "inability to plan income in advance" (level 3). The first author also coded whether the employment-related experiences were evoking strain or activation. Text fragments could be coded with (partly) overlapping codes referring to different uncertainties, efforts, and forms of support, allowing us to focus on interrelations between these dimensions during the analyses. Additionally, text fragments referring to other components of the ESA model (e.g. personal and social characteristics, mental well-being 1 ) were coded with codes referring to these components. A phenomenological perspective was applied when analysing the interviews. The foundational question in phenomenology is "What is the meaning, structure, and essence of the lived experience of this phenomenon for this person or group of people?". As a consequence, in phenomenology the focus lies on exploring how human beings make sense of experiences (Patton, 2002). In line with this approach, attention is paid not only to the occurrence of experiences, but also to the perceptions and feelings of people associated with these experiences (Creswell, 2007;van Manen, 1990).

Employment relationship uncertainty
Employment fragility Work through temporary employment agencies is almost by definition uncertain because of the temporary nature of these contracts in Canada, and because agency workers do not know if and when their employer(s) will offer more work. Some of the interviewees are desperately waiting for a call from their agency every day they are unemployed, which makes it hard to have direction in life on the long run: My agency says, "Here and there, here and there". It's a dog's life now. When we get up in the morning we have to think, "I hope that the agency calls us". We have to stay in the house and wait for the call. We pray every day that they will call us. (Victoria) 2 Adam, a 38-year-old blue-collar worker, experienced an evolution in his feelings of uncertainty towards getting used to changes and adaptations, and because the jobs offered provided a better fit with his capacities over time. He even became motivated to perform temporary jobs from the moment he achieved a feeling of control over his employment situation: When I first started at Temp Agency A, it was a lot of uncertainty because you didn't know if you were going to get out that day or the next. Or you put your name on the list and all that, your name might not come up for two or three days, so you didn't know if you were getting work or anything like that. But then after you get the flow of it and get to know people and all that, it's like, "Okay, yeah, here Adam, go, go!".
Most of the time, Adam worked in his wife's business. He voluntary chose to accept agency jobs if it was not busy in his wife's company. He testified that it gave him something to do instead of sitting at home. However, insufficient notice to accept work offers is often perceived as problematic, particularly in relation to planning childcare and more general household responsibilities. For example, Abigail, a 24-year-old woman, told us that she had to refuse jobs because she could not find childcare at short notice. This is especially problematic for women because generally they are still considered as responsible for the care of their children.
Others, like Elaine, a 28-year-old graphic designer, appreciate the flexibility of accepting or refusing assignments at short notice according to their own needs and preferences, since it provides them with a sense of autonomy and freedom. Uncertainty was not perceived as a problem for Elaine because she felt "in control" over her ability to accept or refuse further assignments: I know a lot of people couldn't do it without just freaking right out, but I did like that. It was kind of a deal where the agency could call you up and, you know, "Hey, do you want to come in today?". It's like if I'm feeling off, I can say, "No, not really, thanks". You know, I appreciate it. This feeling of being "in control" can be mainly attributed to Elaine's skills and creative talent. Kaitlyn, a young single woman, also prefers temporary jobs because she likes the variation and would get bored of doing the same job for a long time.
You go in there, you do a good job and leave a good impression, and then you leave before you get grumpy. And of course, it's all new so you're all excited. I really enjoy working for a temp agency. For Kaitlyn, "temping" fits with her adventurous lifestyle, that is, a combination of working/travelling abroad, studying, doing different temp jobs, and so on. She conceives her current lifestyle as a transitional period in her life.
Finally, the fragility of temporary agency workers' employment relationship seems to be linked to the informality surrounding their employment relationship. Some agency employees testified that they could not trust to receive the correct wage for the work they had performed. According to Stephen, mistakes in pay slips were never in his favour. This led Nelson to characterise temp agencies as institutes that "milk people". Moreover, some agency workers experienced problems in getting paid and getting paid on time by the temporary employment agency.

Earnings uncertainty
Many temporary agency workers mentioned that income insecurity causes a lot of stress, including difficulties in making medium-or longer-term plans. Often, interviewees indicated that they just try to cover their bills but cannot afford big expenses or spend money on social activities. In other words, they do not have the ability to satisfy their needs because of earnings uncertainty. A quote from Bruce, a single man, is illustrative in that regard: The only thing I would like to change is that I would like the income to be regular, so I knew how much money to expect every week because it could disappear in an instant. Like, you could have three or four assignments, and it could be cancelled just like that. So if I was stable, and I could expect a certain amount of money a week, it would make it easier in terms of going out and knowing how much money I have, and sort of budget better. By contrast, for Adam, who worked partly in his wife's business, the income earned through temporary agency jobs was conceived as an extra financial boost for the family income.
Earnings uncertainty also concerns social security. Almost none of the temporary agency workers interviewed was paid when they missed work because of being sick. As Brenda put it, "You don't go, you don't get paid." Stephen testified that he lost a dollar an hour of his hourly wage for the entire month after taking a sick day. These experiences evoked feelings of unfairness and frustration. Similar problems were mentioned in relation to disability insurance or pension benefits. For example, Monica, who has been doing temporary jobs for the last eight years, needed disability insurance, since she required wrist surgery. While performing her temporary job, she had put her health at risk by not wearing her wrist brace. She did not want to show her disability to her employer because this would lower her chances of getting disability insurance, which comes with gaining a permanent contract: I'm afraid because in this position, the other temp had to leave for an operation. So I'm just trying to be so careful. Like, if anybody sees me, I do cry out in pain because it does hurt, but I purposely am not going to wear the brace that I have. And even if I do go to the doctor and it does require something, I'm not going to be able to do it until I'm working fulltime and permanent anywhere because I need the benefits.
As a consequence of being in precarious employment for a long time, many temporary agency workers did not have savings, company pensions, investments, or other financial resources. Some mentioned that they had debts or used their credit cards frequently to make ends meet. Some borrowed money from family and friends, unsure as to whether they could ever repay them.

Scheduling uncertainty
Scheduling uncertainty affected the short-term plans of most temporary agency workers. Our interviewees mentioned that schedules are mostly based on the client-employer's need for flexibility. Moreover, often, schedules are only known at short notice, and agency workers do not always receive information on the number of working hours. This was seen as unfair. Oscar testified that he has to work for as long as is required. Indeed, some temporary agency workers are forced to work long hours, while others like Isabel complained about not getting enough working hours: I am also concerned, why the agencies cannot keep their employees, give us not only one day, even a three days job a week. Why they don't give us like that? And there's even sometimes four hours only, that's it. Especially if you live far and you go to that workplace and to work only for four hours and then you are sent home, there's no more job. It's really difficult.
However, long or flexible working hours are not a problem for everyone. Julia, for example, who developed an interest and expertise in web design through temping, is very motivated to work up to 55 hours a week. She sees this as a challenge: Yah, I think I've just gotten used to it, I'm an A-type personality so I like to be busy, like the challenges.
Likewise, some interviewees stressed that doing temporary jobs has many advantages for themamong others, the flexible working hours: It's great that I can come and go as I please, as long as I show up when I say I'm going to show up. (Kaitlyn)

Employment relationship effort
Effort keeping employed Two issues concerning the effort keeping employed were important in the interviewees' accounts: the effort regarding the constant search for new employment and the effort in dealing with poor treatment at work.
A first main effort for temporary agency workers is their constant search for further employment because of employment instability. Sharon mentioned that "it is a full-time job to find a job". What is particularly frustrating is that efforts seldom yield the desired rewards. Some agency workers try to upgrade their skills by following unpaid training to increase their chances of obtaining a (permanent) job and to invest in their personal development. Often, temporary agency workers register themselves with several agencies, call them daily, or get up very early to queue at the agency in order to be the first to get a job. These people are prepared to accept any kind of job. However, their efforts are often without result, as explained by Ron: First come first served. If I show up at 5:30am like, first guy gets the job. Get there and you're not on the list, and those first on list get to go, and those on the bottom of the list don't . . . I personally hand out over 300 resumes per month if not more, and really even the last two months I haven't received any e-mails or phone calls. I sometimes check my e-mail and phone number on my resume because I am not sure if it is because they are not getting it. For many interviewees, it is hard to sustain their job searches. Some workers even lose self-esteem because of the constant failure to find a decent job: Actually, when I was really down, I even applied at Harvey's, Tim Horton's, and Wendy's [well-known fast-food restaurants in North America] but with no response. At that point, I felt I was not worthy and had no value. I was embarrassed to tell my friends I could not even get a job at Tim Horton's. I felt really bad and thought, "What is wrong with me?".
Dealing with poor treatment (e.g. discrimination) at work is another effort that cannot be underestimated. Howard (50 years old) explained that some agencies do not hire him because of his age. Sarah, a South Asian woman, mentioned that the workers in one of the client-companies where she worked only wanted "their own people" in the company, referring to a certain ethnicity. Besides, many interviewees testified that they had been harassed and discriminated against because of being a temporary agency worker. They mentioned that some permanent employees act as if they own the company and consider temporary workers as inferior. To Helen, permanent workers yelled, "Leave!". Some interviewees also mentioned permanent workers giving the hard jobs to the temps. One of the reasons that temporary workers are treated with disrespect is that temps were often seen as competitors for the permanent jobs in the client-companies: A lot of them, if they know you're from an agency, they'll treat you like shit. Because they think that you're only in that company to steal their jobs. Especially in a unionised spot, really bad. For example, I was with a construction company. We were just there supposed to be for outside clean-up. And they brought in a separate lunch trailer because the union guys didn't want us to be there because they thought we were scabs because we were stealing their jobs. So I mean, like, you get treated like a piece of poop from these unionised guys. (Adam)

Constant evaluation effort
Almost all temporary agency workers stressed the importance of being favourably evaluated in order to get more work offered by the client-company or the agency. This constant evaluation pressure forces temporary agency workers to work hard, accept dirty jobs, and be flexible. An interviewee explained that he did not get new assignments anymore from a temporary employment agency, since he refused to do a dangerous job without safety protection.
Because of the constant evaluation effort, temporary agency workers have to compete with other workers to prove they are the best to keep their job or to gain a permanent contract. This is often perceived as stressful. Justin, a 22-year-old student who combines his studies with working in an accounting firm, mentioned that people "eat their time": they work without charging their time in order to appear more efficient.
Favouritism also plays part in the evaluations made by the temporary employment agency or the client-employer. There is often no commitment from the part of a client-company to keep a temporary agency worker. Adam thinks that temporary agency workers are often "the bottom of the pot for the company" which affects their sense of self-worth.
Being evaluated is not a problem for every agency worker. Elaine knows that she is doing a good job, and she is rewarded for it by her agency by getting offered jobs at more prestigious client-companies. Actually, she benefits from evaluations because they serve as a steppingstone to better jobs: In the agency case, if I do well then the agency knows they can count on me, send me out to further contracts. They know there's a certain level of expertise I can bring, so they can send me out to the more prestigious clients, things like that.

Multiple worksites effort and multiple employer effort
For some interviewees, working on different worksites for different client-employers has advantages. Abigail, for example, mentioned that she liked working in three different jobs because of the social contact and the opportunities to explore different places and tasks. So, for some agency workers, working at multiple worksites and working for multiple employers is not perceived as an effort but instead offers learning opportunities to gain experience in different tasks and environments. In that manner, a temp job can also serve as a stepping stone for a permanent job, as mentioned by Taylor, a warehouse and factory worker: "I use the temporary agency to get my foot in the door". Many others, like Brenda, had difficulties adapting to new work environments all the time: It's hard, it's like you have no belonging; you don't belong anywhere. The agency, they just call you, send you to a place, that's it.
A related problem is the contradictory information workers receive from their agency and their clientemployer, for example regarding working hours and contract extensions. In the case of Rose, the clientemployer told her that she got a week off and could return afterwards, while the agency said that the job was done. In this case, the tripartite employment relationship serves as a negative stressor. Moreover, the strain caused by multiple employers is exacerbated among temporary agency workers who are using different agencies and work for different client-companies. Monica had to turn down her temporary employment agency, since she found a better temporary job through another agency. She was scared that turning down this employer could cause her trouble if she needed another temporary agency job in the future: And then I was offered the other position, so I had to lie to get out of the one I was currently working at because the other one was a little bit more money and it was longer. So that I don't like at all. Because I don't know where I'm going to be and plus it puts me in a bad position of having to turn down. . . I was actually working at the head office of Temp Agency Y, so I was, like, "Please don't", you know. If I get on their bad side, they're not going to find work for me.
A further concern regarding the tripartite employment relationship includes finder fees for agencies, preventing client-companies hiring the temporary agency workers on a permanent basis. However, positive experiences also exist: Yes, they [the agency] stood up for me. I was driving a truck for them [client-employer] for a very low amount of money, and they said that I didn't do those hours, that it couldn't have taken that long to do that. I explained about the traffic, and they said it is not possible. In the end, the temporary agency actually helped me. (Saul) In this case, the agency has a buffering, protecting role for the employees, and can be conceived as a form of support.
Mutually reinforcing relations between employment relationship uncertainty and effort, and the buffering role of support According to the ESA model, uncertainties and efforts are mutually reinforcing each other in relation to mental well-being (see Figure 1). It is the combination of both negative stressors that affects mental well-being most strongly. This is the case both during the search for work and on the shop floor. Further, different forms of support can be interpreted as coping resources that buffer strain and poor mental wellbeing.

Consequences of combining high uncertainty and high effort
The combination of uncertainties and efforts clearly leads to strain in many cases. Victoria explained that she begs agencies for assignments (effort keeping employed), while she is uncertain whether her agency will offer more work (employment fragility): We call the agencies, saying, "Please, please". To tell you the truth, sometimes we have to give something to them, like a present. Nowadays, it is like that: you give and then you can take something. Then they give you maybe two times or three times a week the job. A lot of people are doing that. We have to do this or else they are not going to give the job to us.
Constant failures in finding employment led interviewees to lose their courage and give up their search for a decent job: I just used to look on the Internet sometimes, but when my job ended, I started looking all time, looking everywhere. I would send out my CV for jobs, I looked in the newspaper and on Workopolis, I kept calling the agency. But nothing came. I got very frustrated, and I'm not looking much now. I go to the computer and tell my dad I'm looking, but the truth is, I'm not looking much now. I hope the agency will call me. It is very stressful not having a job. (Nicholas) As with Victoria, we can see an interrelation between efforts and uncertainties in the discourse of Nicholas, a 29-year-old man. The constant search for employment and the uncertainty regarding the ability to find employment are particularly "straining" for him. Because of frequent failures, Nicholas has lost his courage to find a decent job, his goals of personal development, and his direction in life. It makes him feel that he is not a valuable person in the labour market.
These interactive consequences of high employment uncertainty and effort are also taking place on the shop floor. A first aspect is the constant evaluation effort, which becomes particularly problematic when combined with employment relationship uncertainty. Nelson complained that client-companies forced him to work long hours, something he could not refuse out of fear of a negative evaluation, which would cost him his job: If they call back your temporary agency to tell them, "Oh by the way, we asked Nelson to work for another extra hour and he said no". "Okay you don't want the job". And now all of sudden, you are the bad guy because you can't take anymore. You are so tired. You go home, and you become angry with your wife and your kids. It is the job that is the problem. You are not getting enough rest. It is incredible. It is becoming the pattern now. They tell you these are the only jobs they have.
Another example comes from Lewis: No respect. Everything they tell you to do is a heavy job or a dirty job that you don't feel like doing. If they ask you to do it, you have to do it. If you do, the next day they will call you. If you don't do it, they won't call you because you don't want the job. They don't care about you.
Because client-employers evaluate their agency workers on the criteria of productivity and flexibility, and temporary employment agencies on the basis of satisfaction of their clients, many agency workers feel forced to be flexible and work hard. If they don't, they can be excluded from (new) job assignments. Evaluations are seen as tools of exploitation and not as valuable tools aimed at improving the competences and work performances of employees in the long run. These efforts (provoked by an uncertain employment relationship) have negative consequences for agency employees' mental well-being, as demonstrated in the quotation from Nelson. Moreover, the way evaluation is used in temporary agency employment helps to maintain the use of temporary agency employment as a form of disposable labour.
Furthermore, the constant struggle for remaining employed or finding permanent employment is sometimes hampered because of agencies making false promises about permanent contracts (employment fragility). This practice makes temporary agency workers feel frustrated and can affect their self-image: The agency told me the position would be from temp to perm after three months. So, that's it, then I got tired of it. I felt used, you know, because people just show you this nice face, "Oh you're doing great". And I would normally ask in an assignment "How am I doing? How is everything?", and they would say everything is fine. And then that's it. You work your butt off trying to gain that position and then you are gone. Used. So I'm tired of going in, and you feel, I was reading somewhere, "second class", which is right. (Brenda) A last example of the interrelation between efforts and uncertainties is illustrated in a quotation by Oscar. He described how being sick impacted his life: The other thing is that if call in sick, like I did, many temp workers have to go to work sick, like with fever and stuff like that because you cannot afford really to skip a job because you're not being paid for those days you don't work. So it's like you are caught in a circle where you really have to show up every time, and inside you have to think what you're going to do next. So it's a very intensive, I would say mental activity that's going on inside your head. And that's not to your benefit because you don't relax; you cannot really enjoy your life properly.
In this quote, we can see the interplay between earnings uncertainty and employment relationship effort. The fact that Oscar is not paid when he is sick forces him to make the effort of going to work while being ill, which consequently affects his mental well-being.

Employment relationship support as a buffer?
Our interviews reveal the potential role of support as a buffer against the straining effects of the uncertainties and efforts encountered by temporary agency employees. By contrast, a lack of support also acts as an additional cause of stress.
An example is union support. Because temporary agency workers are not unionised in Canada, many of them are in a powerless position regarding their rights as a worker.
Emotional and financial support from friends, family, or the community can be important factors in coping with the negative experiences related to precarious employment. This is especially the case if workers are hoping to improve their situation. Ron, for example, tried to keep positive people around him to support him emotionally and financially in dealing with the uncertainties and efforts he encountered. He stressed the importance of this kind of support because he knew how hard it is to miss it. In the following quotation, he describes how a lack of support can affect the self-esteem of people who have to deal with frequent periods of unemployment: Most people in my situationbecause I know thishaving lost my job before and not having people around me like that. You end up getting very depressed, and you know people don't care about you. People start treating you like crap. You start getting doubts in your head, and they start looking down at you because you are not working. Or you think that they are looking down at you . . . Meanwhile they are not thinking like that at all, but it plays with your head.
Joseph mentioned the support of his family in coping with efforts and uncertainties: Family helps. The support they give . . . My girlfriend helps look for work, so it's not just me. Then I don't feel so overwhelmed.
However, in cases where workers feel trapped in their precarious situation, they can lose their power to cope. In these cases, support cannot buffer the negative consequences of uncertainties and efforts anymore. Lewis, for example, told us that a friend sometimes comes to his house and talks to him to make him feel better. The friend tells him that things will get better, but Lewis does not believe him and does not want his friend to come by anymore. Apparently, at a certain point, support from friends did not help him anymore to cope with the uncertainties and efforts he encountered.
Colleagues can also give support. Abigail testified that her friendly colleagues made her temporary job comfortable: I think it was mostly the people in the place that made it more, like, comfortable for me to be at. I felt, like, "Okay, I want to go to work today", and a lot of places you go to you just, "Okay, I got to go to work". But this is the first time I actually wanted to go to work.
However, building friendship relations with colleagues is not easy for most temporary agency workers. Many of them mentioned feeling like outsiders in the client-companies. Besides, few assignments are long enough to develop relationships with co-workers. The constantly changing workplaces can make them feel lonely: You've never met the people before . . . Like, at lunchtime and stuff, you're, like, "Who are you going to sit with?". Sometimes you just end up sitting by yourself, and it's kind of lonely sometimes that way. (Charlotte) Even if temporary agency workers make friends at work, it is hard to maintain these friendships. Ron mentioned that friendships come and go with a job: I feel like I have contract friends. Every time I get a job, I get a friend, and every time I lose a job, I lose a friend.
Finally, regarding household economic support, many temporary agency workers mentioned that they were paid the minimum wage, which is not enough to cover their expenses. Some workers spoke about temporary agency work as "cheap labour" (Dexter). Almost all of them felt discriminated against, since they knew permanent workers were getting higher wages for the same job. Sharon mentioned that she is "doing more and getting less". Many temporary agency workers were also frustrated about the part of their wage that was claimed by the agencies: They're making all the money. Most of my assignments were, like, $10 an hour. And I would be in a position where I can see the invoice because I was doing receivables, and sometimes it would be, like, $20 an hour. That's very hurtful to know that you are capable of making this much while you're making half. (Brenda) Household economic support, by contrast, can buffer employment strain. Charlotte, a 33-year-old manufacturing worker who combined temp work with her studies, described that she likes a certain degree of routine. Short job assignments through agencies made this impossible. She explained that she stays awake at night and arrives at the new workplace very early in the morning because she does not know how the traffic is going to be. Working in new places regularly causes her stress, although she can handle the stress better, since it is not a financial necessity for her to have a job. In other words, for Charlotte, household economic support partly buffers the negative impact of multiple worksites effort.
Well, there are a lot of different stressors at each type of job. Like, I mean, as a temp, the stressors aren't directly work related; they are not as strong. But you have to worry about travelling and the hours and stuff like that. So it's kind of different types of stress. I don't know if it's less stress. It certainly would be more stress if I needed the jobs though. Then it would be a lot more stress because you don't know. Every day is kind of, like, "What am I going to be doing tomorrow?". Moreover, some temporary agency workers had benefits through their partner. This is an example of financial support at the level of the household buffering strain coming from earnings uncertainty: No benefits from agencies. I'm lucky I have my husband who has benefits. But how about those other people who are just working for an agency? The government never pays for drugs. It's really hard to have no benefits, no dental, no anything, right? (Rose) Most temporary agency workers, however, live in households with a low income and few employerprovided fringe benefits (among others a dental plan, a drug plan, eye and vision benefits, and transportation benefits). Not having a partner or having a partner who is also in precarious employment tends to result in an insecure and poor financial household situation. However, for some families, a low-paid precarious job provides an extra buffer against poverty at the household level when combined with the more stable employment of another family member.

Discussion
This article makes three important contributions to the current literature on the mental well-being consequences of precarious employment. First, it demonstrates that the ESA model, integrating the employment strain model into a social stress approach, is very useful for examining the mental well-being consequences of precarious and atypical employment arrangements. Other work-related stress models (e.g. the demand-control-support model [Karasek, 1979], the effort-reward imbalance model [Siegrist, 1996], the conservation of resources theory [Hobfoll, 2001], the job demands-resources model [Demerouti, Bakker, Nachreiner, & Schaufeli, 2001], and the psychological contract theory [Rousseau, 1995]) concentrate only on the (intrinsic work task-related) demands of the current job. By contrast, the ESA model takes into account that the demands and challenges related to precarious employment are often not only part of the job itself, but also stem from its instability and thus include factors such as the constant search for work. The framework is based on the employment strain model that was introduced by Lewchuk et al. (2011). However, in contrast to previous work by Lewchuk et al. (2011), the theoretical framework presented in this article focuses on both positive and negative mental well-being outcomes of precarious employment. According to the employment strain model, positive experiences can occur if support is sufficient. Lewchuk et al. (2011) refer to this as "precarious sustainable jobs". This study adds to that finding that independent of the support received, temporary agency employment can relate to positive experiences and can activate workers. In particular, it concerns workers who are able to fit their temporary agency work with their general living situation and lifestyle. In those cases, other coping resources such as having control over one's life and the experience of challenges play an important role. The possession of much-demanded skills is also an important factor, since it provides workers with control and more choice in picking jobs. Finally, the results of this study underline a cyclical process through which precarious employment characteristics have an impact on mental wellbeing: precarious employment experiences influence mental well-being, which then potentially influences future experiences and perceptions. This ultimately leads to a negative or a positive spiral of mutually reinforcing experiences.
Second, the qualitative approach of this study offers an in-depth understanding of the experiences of employment relationship uncertainty and employment relationship effort among temporary agency workers. Regarding employment relationship uncertainty, temporary agency workers are often uncertain about whether their employers will offer them more work in the future. However, for some, uncertainty about work offers can be a tool in their career planning. Moreover, it gives them the opportunity to work whenever they want. Uncertainty about the amount of income to expect and about working hours makes it difficult to plan social and household responsibilities. Yet, some agency workers perceive these uncertainties, for example long or flexible working hours, as challenges. Employment relationship effort becomes clear in the experience of discrimination on the shop floor. In addition, it refers to the sustained effort temporary agency workers put into searching for and keeping employment. They have to perform very well, be flexible, and are unable to complain because of the constant evaluation effort they are experiencing. However, being evaluated is perceived as an advantage when it results in more interesting job assignments from the agency. Moreover, agency workers have to deal with different employers and different workplaces. This causes difficulties in adapting to new situations and getting to know new colleagues. Yet, working in different places for different employers can also be perceived as a way to gain experience. Finally, the tripartite employment relationship can be straining if workers are given conflicting orders from agencies and client-companies concerning contract extensions and working hours. However, in some cases, the agency also serves as a form of support for the worker.
The third contribution to the literature is the focus on the mental well-being impact of mutual influences between employment relationship uncertainties, efforts, and support. In their search for work, temporary agency workers suffer more when uncertainties and efforts are combined. Despite putting considerable effort into finding work (e.g. constant search for work, begging for employment, giving presents to the temporary agency office staff), they are confronted with unceasing uncertainty concerning new employment opportunities. This imbalance between efforts and uncertainties causes strain and affects employees' mental well-being. On the shop floor, client-companies sometimes misuse the vulnerable position of temporary agency workers in order to increase their profit and productivity. Their uncertain position forces agency workers to make extra efforts to keep employment (e.g. being flexible, working hard, or accepting dirty or dangerous tasks). This often leads to frustration and hampered mental well-being when confronted with frequent disappointments despite these efforts. Support from friends, family, the community, and coworkers is a coping resource that can buffer the negative effects of precarious employment on mental wellbeing. However, because support is often lacking or insufficient, strain cannot be buffered in many cases.
Temporary agency employment is often associated with minimum wages and a lack of benefits, which increases these workers' dependency on the income and employment stability of other household members. When such material support at the household level is lacking, coping with precarious employment becomes all the more difficult.
In this study, it is assumed that the underlying mechanisms relating precarious employment to mental well-being are similar for different periods and different contexts because the mechanisms were found in the two different pools of interviews from different periods. The use of these two pools enhances the generalisability of theory developed in this study. Nevertheless, the extent and intensity of precarious employment can vary between different contexts and periods. This assumption leads to some recommendations for further research. Future research should test the ESA model in other labour markets, preferably in labour markets with a stricter employment protection regulation. Furthermore, the ESA model can be used to investigate the mental well-being impact of other employment arrangements that are deemed to be precarious (e.g. on-call work, bogus self-employment).
From a policy point of view, it is suggested that attention should be paid to the use of temporary agency employment: the focus should be on achieving labour market flexibility, not on the creation of cheap labour. A possible way to reach this goal is stricter regulation, for example by imposing rules concerning equal wages and employer-provided benefits for temporary agency workers and permanent workers. Such equal treatment regulation is already implemented in some European countries (Schömann & Guedes, 2012). Restrictions on the use of temporary agency work to specific circumstances and the prohibition of hiring fees, preventing workers from becoming stuck in precarious temporary agency jobs, are policy measures that should also be considered. These measures could decrease powerful psychological reactions such as feelings of being used in temporary agency workers. However, non-discrimination regulation alone does not eliminate discrimination between temporary agency workers and permanent workers (Nienhüser & Matiaske, 2006). Hence, complementary measures are needed, for example in the form of (collective) representation of temporary agency workers and stronger systems of control and sanctioning in case of non-compliance with regulations. Another possible measure is to facilitate access to unemployment benefits in view of decreasing financial insecurity. Employers and the government should also invest in the training of precarious workers in order to reduce employment relationship efforts and strengthen their employability. This can empower workers and provide them with feelings of control. In this regard, agencies should play an important role in supporting their workers and making them more employable. A last possibility for decreasing employment relationship uncertainty is by allowing permanent contracts for temporary agency workers. This can be seen as a way to transform numerical flexibility (temporary contracts) into functional flexibility, that is, a type of employment flexibility whereby permanently contracted workers handle different tasks and move between sites. This could diminish the constant job searches of temporary agency employees. Having a permanent contract with the agency provides employees with more financial security, while the clientemployers can still benefit from the flexible character of agency work. Such policy measures would contribute to a "real flexicurity model" where employers' needs for a more flexible workforce at the periphery of their organisational structures are combined with employment relationships that reaffirm the traditional advantages for employees of the standard employment relationship (Bosch, 2004). Notes 1. When analysing the interviews, mental well-being was interpreted as a broad concept, defined as a combination of positive affects (excited, comfortable), the absence of negative affects (anxious, miserable), life and job satisfaction, self-acceptance, positive relations with others, personal growth, meaningfulness in life, autonomy, and environmental mastery (Ryan & Deci, 2001). 2. All names in this article are pseudonyms.