Objective To investigate the pollution characteristics of metals/metalloids in household dust in the cities, China, and to provide a scientific basis for the prevention and control of metal/metalloid pollution in household dust.

Methods According to the daily life scenarios of Chinese residents, samples of household dust were collected from 152 households in five cities in China in 2018 (once in warm season and once in cold season), and the content of 19 kinds of metals/metalloids in the samples were measured by ICP-MS. Rank-sum test was performed for comparison between different types of cities, different wind direction areas and different seasons.

Results A total of 185 household dust samples were measured, and the content of 19 metals/metalloids in the samples ranged from 0.01 μg/g (mercury) to 17 105.42 μg/g (titanium). The content of titanium, barium, and manganese were the highest, with median concentration of 3 351.62, 610.66, and 566.50 μg/g, respectively. The median concentration of cadmium, copper, boron, barium, nickel, and arsenic was 3.04, 1.42, 1.37, 1.35, 1.28, and 1.26 times of the soil background values in China, respectively. The contents of chromium, arsenic and antimony in the household dust of Lanzhou, barium, vanadium, chromium, cobalt, molybdenum and thallium of Mianyang, and vanadium and mercury of Shijiazhuang were higher in the cold season than those in the warm season (Z ranged from -2.979 to -2.042, P < 0.05). The cobalt and molybdenum in the household dust of Luoyang, the barium, vanadium, chromium, cobalt and molybdenum in Mianyang, the vanadium, chromium, nickel and lead in Shenzhen, and the selenium in Shijiazhuang were higher in the downwind area than those in the upwind area (Z ranged from -3.071 to -1.985, P < 0.05). The first-tier cities had a significantly higher contents of zinc of 94.46 μg/g (Z=7.468, P=0.024), nickel of 53.04 μg/g (Z=14.373, P=0.001), and cadmium of 0.47 μg/g (Z=15.654, P < 0.001), and the second-tier cities had a significantly higher contents of copper (46.80 μg/g) and vanadium (84.32 μg/g) (Z were 67.062 and 59.764, respectively, P < 0.001), while the higher contents of mercury, antimony, beryllium, cobalt, chromium, manganese, and barium were observed in the third-tier cities.

Conclusion Nineteen kinds of metals/metalloids were detected in the household dust, and the contents of cadmium, copper, boron, barium, nickel and arsenic exceeded the soil background value by a higher multiple. The overall trend of metal/metalloid content was higher in the cold season than that in the warm season, and higher in the downwind areas than that in the upwind areas. The contents of mercury, antimony, beryllium, cobalt, chromium, manganese, and barium in household dust were higher in the third-tier cities. There were relatively high contents of copper and vanadium in the second-tier cities and relatively high contents of cadmium, nickel, and zinc in the first-tier cities.