All states, except Hawaii and Alaska, require that respitory therapists be licensed. License requirments are mostly based on the certification administered by the National Board for Respitory Care, Inc. (NBRC). The NBRC offers an examination leading to the designation of a Certified Respitory Therapists (CRT). One must graduate from an accredited program and pass the exam to become certified. To learn more about the CRT exam, see our CRT Test Guide.