Thinking of scenarios such as a release of radiation from a nuclear power plant or hazardous chemicals from a factory, tanker or pipelines where an airborne plume is created, what are the pros and cons or potential consequences of recommending or ordering shelter in place versus evacuation as an emergency protective measure? What would be the major issues, concerns, factors or circumstances that would have to be considered in determining which measure to order or recommend? Whichever measure or approach is chosen, what would be the most significant factors or issues affecting the extent or degree of public compliance? Please put references