A group of scientists in Hamilton have uncovered insights into the black residue settling on residential areas near the city’s industrial zone. For many years, locals have raised concerns about a dirty, dark substance covering their properties. The recurring problem resurfaced in early July, with residents experiencing what some described as the most severe fallout in recent memory.
Sarah Styler, an environmental chemistry associate professor at McMaster University, along with Grace Yao, a PhD candidate in Styler’s lab, are part of the study titled “What’s the Grime?” aimed at addressing this issue. Through collaboration with volunteers who gathered samples across the city in 2024 and 2025, the researchers discovered that the soot contains hazardous substances consistent with coal burning. Additionally, higher levels of dust and polycyclic aromatic hydrocarbons (PAHs) were detected near the industrial precinct in northeast Hamilton.
Styler collaborated with Environment Hamilton on this research project, facilitated by a $15,000 grant she received from the university in 2024. Both Styler, residing in east Hamilton, and Yao, based in Corktown, have firsthand encounters with the soot issue. “It’s a long-standing problem,” remarked Styler, noting that archival references to the soot date back to at least the 1950s.
The study involved the collection of soot samples from the homes of 50 volunteers throughout the city using sampling kits. These samples were analyzed at four-month intervals by scientists. Styler highlighted that more dust falls closer to the industrial sector, accompanied by higher concentrations of toxic compounds in that vicinity.
An update posted on the Environment Hamilton website mentioned that PAH levels were elevated during winter compared to summer. While the study focused on 13 different PAHs, Styler emphasized that other harmful substances might also be present in the grime. The team suggested that coal combustion significantly contributes to the creation of the PAHs observed.
Although the researchers cannot pinpoint the industrial sources responsible for the PAHs, Styler expressed that with enhanced monitoring and analytical capabilities, such identification could be possible. The findings align with community expectations, indicating that the soot predominantly originates from industrial emissions near coke plants.
Community members, especially those directly impacted by the fallout, have expressed frustration over the lack of information from official channels. The Ministry of the Environment, Conservation, and Parks is conducting tests to ascertain the probable sources of the soot. Styler affirmed that their research contradicts claims suggesting the soot is primarily road dust, reinforcing community assertions that it stems from industrial activities.
A community meeting is scheduled for Aug. 20 to present the team’s findings, with plans to expand the study to 200 volunteers and delve deeper into the composition of the grime. Additionally, the researchers aim to explore effective cleaning methods for the soot.