Your report on the death from overwork of the Japanese reporter Miwa Sado states that 80 hours of overtime per month is the level at which working hours start to pose a serious risk to health (Journalist died after doing 159 hours of overtime in a month, 6 October). This is far too high a threshold for health problems related to working hours. In 2015, a paper in the Lancet statistically analysed studies from around the world, involving over 600,000 individuals. This found that regularly working 49 hours or more per week was associated with a significantly increased risk of stroke compared with those working 36-40 hours per week. For those working 55 hours per week or more, the increased risk was 33%. There was also a 13% increased risk of coronary heart disease.

This, of course, is aside from the mental health issues that are associated with overwork (and the bullying that often accompanies it), health issues associated with shift working, and the danger posed by fatigued workers in safety-critical occupations. We might also add to this list the health issues associated with precarious employment.

To take one example from the UK, a 2016 survey of universities and further education institutions found that staff, on average, were working two days unpaid every week. Let us not think, therefore, that overwork is a peculiarly Japanese problem. We in Britain need to take a long, hard look at ourselves.

David Hardman

Trustee, London Hazards Centre

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