Read the excerpt about secondhand smoke from the Centers for Disease Control and Prevention’s website. Eliminating smoking in indoor spaces fully protects nonsmokers from exposure to secondhand smoke (SHS). Half of the US population is covered by state or local smokefree laws that do not allow indoor smoking in worksites and public places, including restaurants and bars. Most people have adopted smokefree rules in their home. Still, exposure in the home remains a significant problem. - The home is the primary source of SHS exposure for children. - About 80 million (1 in 4) Americans live in multiunit housing and can be exposed to unwanted SHS in their homes. SHS from units or common areas where smoking occurs can seep into smokefree units. - Many who live in public housing are especially affected by SHS, including children, the elderly, and people with disabilities. Which detail best helps answer the research question "Are smokefree policies effective in protecting people from the dangers of secondhand smoke?"