A study has found that sunlight causes chemical reactions in the dust found on Edmonton's roads.
The research by the University of Alberta, published recently in Environmental Science and Technology Letters, looked at road dust and its components.
"We discovered that road dust ... reacts with sunlight to produce singlet oxygen, which is a reactive form of oxygen that can promote chemical reactions," said Sarah Styler, an atmospheric chemist who conducted the study.
"It's producing this reactive species that could potentially react with contaminants that are also present on the surface of road dust."
Styler, who said the finding was surprising, said it's difficult to know yet what it means for the average person.
"It's early days in understanding the chemistry that happens at the surface of road dust and its ultimate implications," she said. "Our work is really a first step towards understanding the kinds of reactions that can happen on the surface of road dust."
The road dust was made up from exhaust emissions from vehicles, particles from brake pads or tire treads, debris from the road itself and runoff from nearby parks or yards.
Styler's research group has previously studied desert dust, so the goal of this project was to look at how road dust in the city compared.
"Road dust is becoming a much more important part of particulate matter in our cities, and this is, in part, because exhaust emissions [from the tailpipes of cars] are becoming much more strongly regulated," she said.
"At the same time, road dust comes from a really wide variety of sources — it's extremely chemically complex — so it's much more difficult or impossible to regulate.
"So, in the future, what's going to happen is that a larger portion of our city's atmosphere is going to be made up of road dust."
Styler said results from downtown Edmonton are just the beginning.
"We have a variety of other samples we collected around Edmonton in some industrial areas and some more rural areas," she said. "We are going to, in future, compare the reactivity of those particles to the reactivity of the ones we got in downtown Edmonton.
"Ideally, we'd like to collect road dust samples from around the world, too, and get a better understanding of how they react in the environment."