Protection from radiation through distance and shielding can be achieved with an adequate shelter. Being inside a shelter with distance from the source and shielding providing protection will lessen one's exposure.

It provides distance away from the radiation located outside. The shelter acts as shielding and can help prevent inhalation of radioactive material.

Figure 2.1 from the 2017 EPA PAG Manual (as depicted below) illustrates how different building types and location within the building affects external radiation exposure risk.