something else that can help -- cardio pulmonary resuscitation -- or cpr. because most cardiac arrests happen at home -- cpr is a skill we all should learn cpr instructors say -- even if it's not perfect -- simply learning how to do chest difference. 26-35 (sot: chris fielder, red cross cpr instructor) "compressions are the most important part of even when the person becomes unconscious..." fielder says people are often afriad they're going to crack a rib by doing chest compressions. he emphasizes -- cracked ribs are not life threatening -- but cardiac arrest is. the red cross offeres cpr classes online-- and in a classroom. once you've learned the skills needed, you can get certified. even if you don't get certified - you're learning valuable skills you can use if you ever find youself in an emergency situation. coming up on wavy news ten at five- thirty - five americans held prisoner in iran -- closer to returning home tonight. we'll hear from the family of jason rezaian -- on how he's recovering from his 18 month ordeal. then a little later - travel plan

. >>> cardio pulmonary resuscitation, cpr, it's a still health officials say we should learn. what you need to know, because you never know when it may be the tool you need to save a life. >> you are going to sustain life. it's better than doing nothing at all. >> reporter: chrisfielder has been with the american red cross for 25 years and teaches cpr classes. he emphasizes with or without formal training. >> if it's not perfect, if you are not certified. >> reporter: people who find themselves in an emergency situation can make a difference. >> one, two, three. >> reporter: simply by learning chest compressions. >> compressions are the most important part of cpr. circulating that blood, because there is going to be some oxygen still left in those lungs, even when the person becomes unconscious. one, two, three, four, five. the clicking that you hear is a mechanism in the manequin that kelsey that -- that you are compressing the proper depth. they may crack a rib. but a cracked rib isn't life-threatening. cardiac arrest is, and that's why learning cpr is so critical. >> it's b