Not all states or regions permit an individual to practice in the medical field especially those involving with delicate responsibilities without any license or certification. This permit ensures that the practitioner is expert with the job and can deliver the desired service expected by most patients. Just like working as a Respiratory Therapist, anyone doing the job should be certified before they can legally perform. To obtain this certification, passing the exam administered by the National Board for Respiratory Care has to be accomplished. It would be much better that even before you get trained in a program, you should have already known the prerequisites for taking the exam.