摘要：Here we propose an explanation for this phenomenon. Toxicants are not distributed homogeneously in dust according to particle size; particle size distribution of settled dust varies with its spatial position. Thus, distribution of polybrominated diphenyl ethers (PBDEs) will vary with the particle size of dust and the spatial position of settled dust, as well as the location of PBDE sources, such that PBDE levels in settled dust on the floor will be different from those of settled dust above the floor (Björklund et al. 2012; Wu et al. 2010). Because of the spatial position of particles, humans are likely to be exposed only to particles of specific sizes. In addition, exposures to children and adults may be different because particles to which children and adults are exposed often have different spatial position and particle size distribution (Cao et al. 2012; Ruby and Lowney 2012). In addition, the reliability of human exposure assessments may be substantially influenced by between-room and within-room spatial variability of PBDE concentrations in indoor dust (Muenhor and Harrad 2012).
