A comparative study on physicochemical characteristics of household dust from a metropolitan city and a remote village in China

The physicochemical characteristics of household dust in a typical metropolitan city (i.e., Beijing, the urban region) and a remote village in western of China (the rural region) were investigated and compared. The results show that the particles of household dust in both the regions could be classified as six types: micro-aggregates, biogenic, spherical, subrounded, subangular, and angular in morphology. Most dust particles were found to belong to the latter three types and belonged to mineral particles. The average particle size (aerodynamic equivalent diameter) of household dust was 16.1 and 14.9 μm in the rural and urban regions, respectively. Dust particles with diameters 10-20 μm were the highest by number in the both regions, while dust diameters from 30 to 40 μm and from 20 to 30 μm were the highest by volume in the urban and rural regions, respectively. The minerals in household dust particles in both the rural and urban regions were primarily quartz, albite, calcite, and dolomite. The average percentages of macro-element species (Si, Al, Ca, Fe, K, Mg, Na, P, and Ti) in household dust in the rural and urban regions were lower than those in the corresponding outdoor dust and their background values, except for Ca. Silicon, Al, Ca, Fe, and K were the predominant elements distributed in household dust in both the rural and urban regions. The concentrations of the studied macro-elements in the rural household dust were lower than those in the urban household dust, being in agreement with the relationship of the reference crust element content in the rural and urban regions. The average percentages of the ions in the rural and urban household dust were generally higher than those in the corresponding outdoor dust. The levels of SO42−, NO3−, Cl−, and Ca2+ in the urban household dust were higher than those in the rural, owing to human activities. The deposition rate of household dust in the rural region (i.e., 15.3 ± 2.6 g m−2 year−1) was approximately 10 times greater than that observed in the urban region due to worse tightness of the houses. Dust at homes was one of the significant sources of PM10 in the residential environment through resuspension, and the studied properties of household dust are closely related to human health. Household dust in both the rural and urban regions of China should not be ignored.