Method Development for Settled House Dust Resuspension to Isolate PM10 for Subsequent Characterization

Settled house dust is a relevant medium to assess residential chemical exposure through ingestion and inhalation. Inhalation of airborne particles with a diameter less than 10 µm (PM10) can have adverse health effects. Understanding the chemical composition of PM10 in house dust is needed for human health risk assessment. However, separation and collection of PM10 from house dust in sufficient amount for subsequent characterization represent a technical challenge. This study aimed to develop a method to resuspend settled house dust and collect its PM10 fraction for further chemical characterization.

Using a vortex, we resuspended house dust sample (< 80 µm) in a sealed flask. The generated airborne particles were entrained by an air stream and a cyclone removed particles larger than 10 microns. A line splitter, after the cyclone, allowed for simultaneous collection of PM10 on two in-line polytetrafluoroethylene filters (0.45 µm), and PM10 real time aerosol monitoring (mass concentration and size-fraction) using a DustTrakTM DRX aerosol monitor. We optimized aerosolization parameters to collect sufficient PM10 mass for later characterization.

Scanning Electron Microscopy analysis confirmed that the collected dust was consistent with PM10. The amount of collected PM10 depended on the nature of the dust (e.g., stickiness) and varied from 0.08 ± 0.01 % to 4.68 ± 0.27 % of the initial sample weight (3 g). The method yielded consistent results within samples (coefficients of variation of triplicates ≤ 16 %; average 20.44 ± 16.95 % ), except for a few samples with variability up to 57 %. The mass of PM10 collected on filters ranged from 2.19 to 143.14 mg. The dust resuspendability and the mass of PM10 collected were minimally impacted by environmental parameters (relative humidity and temperature) and dust organic content.

The developed methodology provides a simple and fast alternative to other labour-intensive and time-consuming methods and effectively separates and collects PM10 from settled dust for subsequent characterization. This will help in advancing chemical characterization of PM10 to refine risk assessment of residential chemical exposure.