A group of scientists based in Hamilton has unraveled the mystery behind the soot accumulation in neighborhoods adjacent to the city’s industrial zone. Over the years, local residents have raised concerns about a dark, sooty residue that has been a persistent problem, resurfacing notably in early July with what some described as the worst fallout in recent memory.
Sarah Styler, an associate professor specializing in environmental chemistry at McMaster University, along with Grace Yao, a doctoral candidate under Styler’s guidance, are leading a research project titled “What’s the Grime?” aimed at addressing this specific issue. Through a comprehensive sampling effort conducted in 2024 and 2025 across various city locations, the team discovered that the soot comprises harmful substances consistent with coal combustion. Moreover, elevated levels of dust and polycyclic aromatic hydrocarbons (PAHs) were detected particularly in the vicinity of the industrial district in northeast Hamilton.
The study, supported by a $15,000 grant awarded by the university in 2024, involved collaboration with Environment Hamilton. Styler, residing in east Hamilton, and Yao, based in Corktown, personally experienced the impact of the soot issue. Highlighting the longstanding nature of the problem, Styler mentioned uncovering references to the soot in historical news archives dating back to at least the 1950s.
Utilizing sampling kits distributed to 50 volunteer households across the city, researchers collected soot samples at regular four-month intervals for analysis. The results indicated a higher deposition of dust nearer to the industrial sector, accompanied by an increased presence of toxic compounds in those regions.
Styler emphasized that the study’s focus on 13 different PAHs revealed only a fraction of the potential toxic elements present in the grime, which she described as a viscous mess. While acknowledging resource constraints that limited a comprehensive analysis of all grime components, Yao stressed the significant role of coal combustion in generating the observed PAHs.
Despite the inability to pinpoint specific industrial sources responsible for the PAHs, Styler expressed optimism that enhanced monitoring and analytical capabilities could facilitate such identification in the future. The findings, according to Styler, validate residents’ long-held suspicions that industrial emissions are a primary source of the soot contamination, particularly in neighborhoods near coke plants.
As the research team prepares to disclose its findings at a community meeting on August 20 and submit a manuscript for peer review, plans are underway to expand the study to include 200 volunteers and delve deeper into the examination of various grime constituents. Additionally, the researchers aim to explore effective cleaning methods for the soot, addressing a critical aspect of the ongoing environmental concern.