In some BSC work, radioisotopes solutions are used. These solutions could give off radioactive vapors which would pose a Beta and even Gamma radiation hazard. Since a HEPA filter will not stop vapors, it is expected that the radiation will leave the BSC and exit the building. Prior to accessing and changing a HEPA filter, it is good practice to have a health physicist assess and document that the BSC is free of radiation hazards or to supervise any safety measures required by a radiation hazard if it exists. The HEPA filter itself would be decontaminated as biological and/or chemical waste (see the other sections), prior to removal and be disposed of a non-hazardous waste unless otherwise regulated. If the HEPA filters did contain radioactive waste, the health physicist would advise on proper disposal procedures.