by employers, one fifth to three fifths of those expenses could be attributable to on-the-job productivity losses. Complementing that study, Schultz and Edington provided a detailed review of the effects of certain health conditions on productivity. These authors examined conditions such as allergies, arthritis, chronic pain, diabetes, and mental health disorders. The studies in the review showed, for example, that increases in pollen are associated with decreased performance. Moreover, Schultz and Edington noted that chronic pain had to be studied more thoroughly to better understand its effects on productivity. Poor health and exhaustion Exhaustion and future poor health are often other consequences of presenteeism. For example, Bergstrom, Bodin, Hagberg, Aronsson, and Josephson found that sickness presenteeism was a risk factor for future sick leave. Furthermore, in their study of job demands and presenteeism, Demerouti et al. found that presenteeism resulted in increased exhaustion. Presenteeism can also have an effect on occupational injuries for workers. A 2012 study from the National Institute for Occupational Safety and Health showed that workers with access to paid sick leave were 28% less likely overall to sustain nonfatal injuries than workers without access to paid sick leave. Workplace epidemics In the case of an infectious disease such as influenza, a culture of presenteeism will inevitably also lead to further infections throughout the workforce, compounding the ill-effects and leading to a much wider problem. In a 2014 survey by Canada Life Insurance, over 80% of respondents stated that they had become ill as a result of an infection contracted in the workplace. Measurement of presenteeism and its impact on productivity Scholars have often measured presenteeism in terms of how often an individual attends work while unhealthy. For instance, Aronsson et al. asked participants to what extent over the past year they had gone to work despite feeling they should have taken sick leave. Respondents could choose from never, once, between two and 5 times, and more than 5 times. Other researchers have examined the frequency of presenteeism by asking participants a similar question. The responses, however, were on a scale of "spells of one day presenteeism, spells of 2-4 day presenteeism, and spells of 5 day or more presenteeism." Aside from measuring the frequency of presenteeism, scholars often look to measure the effects of poor health on job productivity. The Work Limitations Questionnaire (WLQ) is often used to perform this task. With 25 items, it examines