While posture at work is recognised as a potential occupational hazard, research now links prolonged sitting with premature mortality, heart disease and diabetes. The potential adverse health risk of sedentary time needs to be considered separately to the lack of physical activity outside work hours. This follows recent evidence that (as a population health risk) reducing total time spent sitting may be at least as important as increasing participation in physical activity- in fact, 30 minutes of physical activity is as protective an exposure as 10 hours of sitting time is a harmful one. For instance, an employee may meet the minimum recommendations for physical activity by doing regular structured physical activity (such as a brisk walk or cycling for at least 30 minutes at 5 sessions per week) but typically sit for prolonged periods of the day - still placing the individual at risk. The evidence is sufficiently strong that: