Previous studies suggested that heavy metal concentrations in indoor dust are affected by house type, structure, and traffic activities; this is another possible source for cadmium exposure (Meyer et al., 1999; Tong and Lam, 1998). In the present study, we found that adolescents living in a multifamily or commercial building had higher blood cadmium levels than those living in apartments. This is the first in vivo evidence that blood cadmium levels in humans can be affected by the type of housing. Multifamily houses might have a higher risk of exposure due to poor indoor air quality, since
they tend to be older buildings with poor ventilation systems, which accumulate and/or simply move air pollution from unit to unit. Since commercial buildings are mainly located in urban areas with high traffic density, the inflow of outdoor air pollution could contribute to increased blood cadmium levels among residents of commercial buildings. As ambient cadmium concentrations in residential environments were not assessed in KNHANES, further studies are needed to explain the effect of housing type on blood cadmium levels in residents.