in joplin. what makes the difference between whether or not someone survives. >> number one, access to air. if you're caught in a tornado, some people have access to air and some don't. secondary will be access to water because you can live for several days without water. after that, it would be whether you have a crush injury and whether in injuries you have get infeed. >> and in joplin, there has been some concern for water. clean water. >> exactly. they're telling residents now to boil their water before drinking it. >> is that enough? >> yeah. the things they're concerned that might have gotten into the water, boiling can take care of it. >> it's amazing because when you look at the pictures, those are things you don't think about. you think about power, electricity, but not water. >> and you don't think about infections, things that are less visible. you think about the things we're seeing now.