The 30 years following the end of the Second World War saw a marked improvement in the health status of Canada and other western, industrialized countries. Mandatory public health measures, including mass immunization, sewage disposal, water purification and the mandatory pasteurization of milk, had substantially decreased the incidence of communicable (i.e., contagious) diseases.

At the same time, years of advocacy efforts by labour unions, community activists and progressive political movements led to the development of the “social safety net” and other economic reforms that resulted in substantial progress towards the elimination of poverty, poor housing and unhealthy living conditions.

As a result of these measures, chronic diseases (e.g., cancer, heart disease and stroke) replaced communicable diseases as the leading causes of mortality in Canada and the western world.

This resulted in a shift in public health practice that placed increased emphasis on addressing the risk factors contributing to these diseases (e.g., tobacco, high fat diets, alcohol and physical inactivity) through the promotion of healthy lifestyles.