Residential buildings are less protective and those with lighter weight walls lack adequate, above ground protection.

Most people in non-residential buildings are adequately protected, particularly below ground or in the building center. We find that indoor radiation protection varies by orders of magnitude. This approach provides a consistent, quantitative understanding of US building protection and, when combined with the distribution of people among different buildings, can assist in selecting emergency response strategies. We provide here a high-level modeling analysis of modern US building protection based on a novel radiation protection building attribute taxonomy, a new building protection model, compilation of prior experimental results, and nationally representative building survey data. However, most US building types, particularly non-residential buildings, lack quantitative estimates.

Being indoors (sheltering) reduces radiation exposures resulting from nuclear fallout or a power-plant accident.

Nuclear Fallout Shelter Definition