Sitting is the new smoking. Eight hours at a desk is as bad as a pack a day. Your spine is collapsing, your metabolism is dying, your circulatory system is filling with the sluggish blood of office sloth. Stand-up desks went from optional to mandatory across half of corporate Australia. There are productivity newsletters about it. There are ergonomic consultants. Your physiotherapist nodded gravely.
Smoking causes about 8 million deaths a year globally and is the single largest preventable cause of death and disability on the planet. Sedentary behaviour is associated with elevated risk of cardiovascular disease, type 2 diabetes, and some cancers, but the actual risk is roughly an order of magnitude smaller than smoking, the mechanism is different (mostly mediated through metabolic and circulatory effects, not direct carcinogenesis), and most importantly, the harm is largely undone by regular exercise. A 2016 Lancet meta-analysis of more than 1 million people showed that 60 to 75 minutes of moderate activity per day eliminated essentially all the excess mortality risk from prolonged sitting. Smoking is not undone by exercise. Standing desks have not been shown to deliver meaningful health benefits over chair-plus-walks; what helps is breaking up sitting with brief movement every 30 to 60 minutes. The 'new smoking' framing is a useful nudge to take a walking break. As an actual epidemiological claim, it is wrong by a factor of about ten.