Teleworking is a designation that dates back to the 1970’s . It refers to work outside the principles of companies or other organizations, which determines the almost mandatory use of information and communication technologies (ICTs) .
Nowadays, it is more and more frequent to observe employees out of their usual offices or workplaces . They work in conference rooms, in clients’ offices, at coffee shops, at home, in their cars, at airports and anywhere there is internet connections. People are working in these places at all times of the day (during usual working hours, at night and on weekends) using a wide variety of ICTs, including, mostly, internet, smartphones, home computers, laptops, tablet computers, teleconferencing, and videoconferencing .
During the COVID-19 pandemic, more than 3.4 billion people in 84 countries have become confined to their homes, as estimated in late March 2020, which potentially translates too many millions of workers temporarily exposed to telecommuting . Strict social distancing measures were applied in Portugal, as well as in other European countries, including nationwide lockdown . The first lockdown, during the first wave of the COVID-19 epidemic in Portugal, took place in March 18 and remained until mid and late May. Telework became obligatory in March 19 until early July. Hence, telework was forced.
Telework gave workers the opportunity to work from their homes or elsewhere, with less time spent travelling to work, with higher autonomy and flexible timing . However, findings from research developed before COVID-19 pandemic showed that telework could have both positive and negative effects, depending on teleworkers’ job profiles, on dimensions of job quality measured, on support received from employers, on personal preferences, as well as on family structure .
Previously described positive effects of telework include improvement of job satisfaction  and work-life balance ; and less work-life conflicts . Major negative effects are physical and mental health adverse effects (mental distresses, as stress, anxiety, depression, and physical conditions as work-related musculoskeletal disorders) which can arise related to isolation, limited mobility in home, working conditions, number of working hours and breaks; as well as unbalance between work demands and workers abilities [11,12,13].
The Occupational Health intervention becomes very difficult in what concerns about telework, by the lack of knowledge of concrete workstations . Thus, this is nowadays a major (and growing) Public and Occupational Health challenge. The working conditions such as lighting, indoor air quality and thermal conditions are frequently diverse and unknown. In addition, work overload (physical and/or mental) can be increased causing potential negative effects on health . The room in which worker develops occupational activities in the household is usually unknown, which is also fundamental for occupational risk management . The psychosocial risks of teleworking are even more difficult to assess. That is because they are not restricted to cognitive, emotional, or mental constraints. Telework can be an occupational hazard for work-related stress and anxiety, depression or even chronicity of some of these health events .
For most remote employees, telework came with the COVID-19 pandemic being their first teleworking experience . Parents were apparently forced to support their children during office hours with the closure of schools and many teleworkers didn’t have a private room specifically designed for work, and/or internet connection and/or adequate digital devices to work and/or for children’s’ distance learning.
Studies performed in different countries have been describing the negative effects of telework during the COVID-19 pandemic in physical  and mental health outcomes . Telework during COVID-19 crisis was described affecting workers well-being, job satisfaction, work-life balance , and also productivity .
However, there is still little research concerning this organizational work. The COVID-19 pandemic offered a unique opportunity to investigate telework, as such a large number of workers in teleworking had never been observed in the past. The first step to better understand the possible health effects of telework is to explore which are the major determinant factors of telework satisfaction, as people with worst levels of telework satisfaction should be those more at risk of having the negative effects of it. Thus, this study aimed to characterize telework during the first wave of the COVID-19 epidemic in Portugal and to identify the major predictors of telework satisfaction considering sociodemographic characteristics, self-perceived health, concentration at work, organization of working time, work-life balance, work disconnection, working conditions in an Occupational Health perspective, as well as organizational demands, namely, flexibility and organizational trust.