Thoracic Fraction (PM10) of Resuspended Urban Dust: Geochemistry, Particle Size Distribution and Lung Bioaccessibility

Abstract

A fluidized bed aerosol generator was connected to a 13-stage cascade impactor (nanoMOUDI) for the size fractionation of urban dust (<10 µm), followed by the gravimetric analysis of loaded PTFE filter samples. This method was used to characterize the PM10 (thoracic) fraction of road dust sampled from expressways, arterial roads and local roads in Toronto, Canada. The fine particle fractions (<1.8 µm) of all the studied samples accounted for 51–72% of the resuspended PM10 (by weight). Elemental analysis using ICP-MS and ICP-OES revealed an overall trend of element enrichment in the <1.8 µm fraction compared to the coarse fraction (1.8–10 µm) of the road dust. By contrast, archived house dust samples displayed the reverse trend for most elements. The lung bioaccessibility of target elements (Al, B, Ba, Co, Cr, Fe, La, Mn, Mo, Sb, Sr, Ti, V and Zn) was assessed for each road dust fraction using 0.1 M ammonium citrate (pH 4.4) to simulate intracellular fluid and Gamble solution (pH 7.2) to simulate interstitial lung fluid. The <1.8 µm fraction of local road dust displayed significantly higher bioaccessibility (p < 0.05) for Zn when using Gamble solution, and for seven out of the 14 target elements when using ammonium citrate. These results show the importance of characterizing the fine fraction of road dust.

Characteristics of Potentially Toxic Elements, Risk Assessments, and Isotopic Compositions (Cu-Zn-Pb) in the PM10 Fraction of Road Dust in Busan, South Korea

“…The average concentrations of Co, Ni, Cu, Zn, Cd, Sb, Pb, and Hg in the PM 10 fraction of road dust were 1.1 (Ni)-4.1 (Hg) times higher than those of the bulk road dust samples [48]. The concentrations of PTEs in this study were lower than that of the soil pollution standard for roads and factory sites in Korea [74]; however, they were higher than the fine particulate fraction of road dust in other cities [14,16,21,57,61,67,69,70,75].…”

“…1 Adamiec et al, 2016[61] (road-deposited sediment);2 Padoan et al, 2017 [66] (road dust);3 Adamiec and Jarosz-Krzemińska 2019[57] (sidewalk dust);4 Zhao et al, 2010[67] (road-deposited sediments);5 Bi et al, 2013 [68] (road dust);6 Levesque et al, 2021[69] (urban dust);7 Fujiwara et al, 2011 [70] (road dust);8 Kong et al, 2012 …”

Selection of metric for indoor‐outdoor source apportionment of metals in PM 2.5 : mg/kg versus ng/m 3

“…As settled dust is both a repository and a source for a diverse range of contaminants, 15,100 future PM source apportionment efforts would benefit from exploiting the elemental composition of house dust as a valuable indicator of indoor sources. Size fractionation of house dust indicates that an abundance of fine material is available for resuspension and potential inhalation exposures, with fine particles (<1.8 µm aerodynamic diameter) constituting about 25% of settled dust by weight 101 . Future studies would benefit from solid‐phase speciation techniques to identify sources of PM‐bound metals: for example, Huggins et al 102 were able to distinguish Cr‐spinel in urban PM (NIST 1648) from Cr(III) sulfate in diesel PM (NIST 1650) using synchrotron X‐ray techniques.…”

“…Size fractionation of house dust indicates that an abundance of fine material is available for resuspension and potential inhalation exposures, with fine particles (<1.8 µm aerodynamic diameter) constituting about 25% of settled dust by weight. 101 Future studies would benefit from solid‐phase speciation techniques to identify sources of PM‐bound metals: for example, Huggins et al 102 were able to distinguish Cr‐spinel in urban PM (NIST 1648) from Cr(III) sulfate in diesel PM (NIST 1650) using synchrotron X‐ray techniques. Such speciation techniques could elucidate differences in the elemental composition of indoor and outdoor particles, such as those observed in the present study (Figures 4 and 5 ; Appendix S2 ).…”

Relationships between House Characteristics and Exposures to Metal(loid)s and Synthetic Organic Contaminants Evaluated Using Settled Indoor Dust

“…This recommendation is consistent with the conclusion by Cao et al [ 29 ] that risk assessments should focus on the <100 μm particle size fraction of indoor dust, based on observations that concentrations of toxic chemicals in dust commonly increase as particle size decreases. Additionally, finer dust fractions have the advantage of greater analytical homogeneity [ 16 , 22 , 30 ] and greater relevance for estimating inhalation exposures to resuspended dust [ 7 , 31 ].…”