Tenability analysis along with computational fluid dynamics is a recognized method of atrium smoke control analysis by NFPA 92, Standard for Smoke Control Systems. Tenability analysis evaluates the following threats to life: thermal radiation exposure, heat exposure, toxic gas exposure, and reduced visibility. In dense smoke, people see poorly and often become disoriented which prolongs exposure time of the other threats. Also, falls from balconies can result from reduced visibility. This paper discusses these threats as they apply to atria smoke control.