Residents question health impact of smell from Stoney Creek landfill after air testing comes back clean

Residents of Hamilton's Stoney Creek Mountain remain concerned about the health impacts of a nearby landfill, despite results from recent air quality testing by the city, after what they say have been months of near-daily "unbearable" smells permeating the neighbourhood.

The air-monitoring results, which the city said met standards set by the Ministry of Environment, Conservation and Parks (MECP), were shared earlier this month — just a few days before a public school board committee decided to pause plans of a new school in the neighbourhood.

Kathleen Taylor, who has been living near the intersection of Highland Road West and Picardy Drive for four years, said she's concerned about her health and that the city's testing was not done at the time of the day when the smells are strongest.

"[The smell] burns our eyes and lungs, gives us headaches," she told CBC Hamilton.

The odour, which Taylor said is like a "more powerful" cat spray, seemingly comes from the GFL Environmental facility on 65 Green Mountain Rd. W. Other neighbours have described the smell as rotten eggs or garbage.

The MECP conducted air monitoring in the summer around the facility. The report was shared with Hamilton Public Health, who stated in an update on Sept. 15 that measurements were below ministry standards.

"No violations were found during the August 2023 monitoring survey period," read the city's report.

The report said hydrogen sulfide — a colourless gas that smells like rotten egg — was the "most likely source" of the smell coming from the leachate pond at the landfill.

One exposure to high concentrations of hydrogen sulfide "can cause a long-lasting condition like asthma," according to the Canadian Centre for Occupational Health and Safety.

However, Hamilton Public Health said there's no imminent public health hazard due to the hydrogen sulfide, as the levels found were very low, at 0.0084 parts per million (ppm), in one instance.

The province's website outlines some guidance around restricting hydrogen sulfide. For instance, in livestock facilities, the province says concentrations of it must not exceed 10 ppm for full-time workers.

But Taylor questioned the testing results.

"The biggest issue with that is that all the samples seem to have been done when it was not very odorous," she said.

The report said testing was done at various times of day, over the course of nine days, between the hours of 8 a.m. and 5:30 p.m., but Taylor said the smells usually start to get bad after 8 p.m.