ABSTRACT
When the Montreal Protocol was signed in 1987, the transition to alternatives for ozone-depleting substances (ODSs) began in earnest. New blowing agents had to perform well and meet safety, cost and environmental criteria. From an environmental standpoint, alternatives were evaluated for impacts on global warming, local air quality and human health, in addition to ozone depletion. Alternatives also had to be safe, with any additional risks mitigated, and had to come with a reasonable price tag and create a product that satisfied technical and consumer standards. Balancing these criteria was not always easy.
