Built environment health research: the time is now for a Canadian network of excellence.

Every generation since World War II has faced its own great public health challenges. In the post-war period, the challenge was the integration back into society of young men and women who had fought a war that took a terrible toll on life and spirit; in the 1960-70s, efforts to control or eradicate smallpox, polio and malaria dominated; in the 1980-90s, tobacco control, heart disease, stroke and HIV/AIDS commanded attention; and in contemporary times, SARS, the H1N1 flu epidemic, mental health and a host of natural and human-made catastrophes have been added to the mix. But of all the great public health challenges, the global epidemic of obesity has emerged as the nemesis of our generation. The numbers paint a grim picture. Obesity is a disorder in its own right, but more pervasively it is also the gateway to many other chronic conditions. The public health and medical care costs attributable to obesity are staggeringly large, and the personal and social costs are not far behind. It is against this backdrop that we offer this special supplement on the built environment and health from a Canadian perspective. Why this supplement, and why now? While it is clear there is an urgent need to take action to address obesity, particularly in children, it is also very apparent that the empirical body of evidence regarding the determinants of obesity – especially those most upstream, such as the built environment, time use and technology change – is only now taking shape. The sense of urgency to halt the childhood obesity epidemic has helped catalyze political processes in some local jurisdictions aimed at making environmental changes by altering public policy. We need new research, especially as it relates to Canadian cities, to indicate which policydriven built environmental factors are the most important contributors to obesity, and to understand the mechanisms through which they work. Such evidence is critically needed to deepen the policy debate, leading to action with greater promise of decreasing childhood and adult overweight and obesity in Canada. The articles in this supplement present current Canadian evidence supporting the impact of the built environment on health, 1-11