Quantification and Characterization of Metals in Ultrafine Road Dust Particles
- DOI
- Language of the publication
- English
- Date
- 2021-11-26
- Type
- Article
- Author(s)
- Beauchemin, Suzanne
- Levesque, Christine
- Wiseman, Clare L. S.
- Rasmussen, Pat E.
- Publisher
- MDPI
Abstract
Road dust is an important source of resuspended particulate matter (PM) but information is lacking on the chemical composition of the ultrafine particle fraction (UFP; <0.1 µm). This study investigated metal concentrations in UFP isolated from the “dust box” of sweepings collected by the City of Toronto, Canada, using regenerative-air-street sweepers. Dust box samples from expressway, arterial and local roads were aerosolized in the laboratory and were separated into thirteen particle size fractions ranging from 10 nm to 10 µm (PM10). The UFP fraction accounted for about 2% of the total mass of resuspended PM10 (range 0.23–8.36%). Elemental analysis using ICP-MS and ICP-OES revealed a marked enrichment in Cd, Cr, Zn and V concentration in UFP compared to the dust box material (nano to dust box ratio ≥ 2). UFP from arterial roads contained two times more Cd, Zn and V and nine times more Cr than UFP from local roads. The highest median concentration of Zn was observed for the municipal expressway, attributed to greater volumes of traffic, including light to heavy duty vehicles, and higher speeds. The observed elevated concentrations of transition metals in UFP are a human health concern, given their potential to cause oxidative stress in lung cells.
Plain language summary
Health Canada is responsible for the assessment and management of health risks to Canadians associated with exposure to products and chemicals in the environment. In urban environments, resuspension of road dust can be a source of nano-scale ultrafine particles (UFP) in the air. The chemical composition of UFP remains ill-defined. This study identifies key metals and determines their concentrations in UFP isolated from different road dust sweepings collected from expressways, arterial roads and local roads in the most densely populated Canadian city of Toronto. The work was conducted in collaboration with the University of Toronto. The results show that key transition metals often associated with vehicle emissions such as Cr, Cd, V, Zn concentrate in UFP. The capacity of transition metals and UFP to induce cellular oxidative stress is known to play a central role in the development of respiratory diseases. The implications of the results for human health is addressed in a brief discussion. The study advances our understanding on the metal composition of UFP, which is critical for assessing their toxicological impact on human health. Data obtained will be useful to support Health Canada’s Chemicals Management Plan, as well as Toronto’s Clean Roads to Clean Air program.
Subject
- Health,
- Health and safety