The National Building Code of Canada prescribes stair tread width at a minimum of 21 centimeters (or 8 1/4 inches). In Canada, nearly one person dies falling on a set of stairs every day, and more than 270 people end up in the hospital, according to the Canadian Public Health Association. Elderly people make up two-thirds of those cases.
A study by the non-profit organization SmartRisk estimated that treating the resulting trauma, as well hospitalization and emergency room visits, cost the health care system $580 million in 2012. Researchers suggest that as little as two more inches of tread width would create much safer footing on stairways.
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