Here's the long answer:
In the US we did not develop comprehensive hazardous materials regulations until 1985-1987 in the model building and fire codes. Prior to that we had regulations but they were not correlated and more importantly, were not tied to a building’s occupancy classification, a material's hazard classification, and how it was used. As a result a task group was formed that worked on completely revising the legacy building and fire codes by having comprehensive hazardous materials regulations.
Part of these early requirements included requirements for radioactive, asphyxiant and irritant gases. After some limited experience in which building owners started spending big dollars on gases that really presented minimal risks, the codes reduced the requirements for irritant and asphyxiant gases. Later changes essentially exempted radioactive gases as they are regulated in the US at the State and Federal level and its requirements are driven by the isotope and its respective hazard. However, a number of fire code officials were concerned about storage of simple asphyxiant gases in a room and having a release. Since these gases are colorless and odorless, some officials were concerned about the potential of a person walking into a room where a simple asphyxiant gas leak has occurred and the person is incapacitated due to an O2 deficient atmosphere. To minimize this risk, Section 3007 (previously from the Article 74 of the legacy Uniform Fire Code) was developed. Section 3007.2 requires either natural or mechanical ventilation that provides 1 CFM/square foot over the storage area.
As to radioactive gases, I don’t believe they should be regulated by the IFC.