High levels of lead found in air around Kahnawake high school, near Montreal

The Mohawk Council of Kahnawake has released preliminary test results it says show high levels of lead in the air close to the community’s high school.

Lead levels when the wind was blowing west towards the community were on average 1.5 times higher than the provincial standard of 100 nanograms per cubic metre, the council said. However, lead levels were “well below” the threshold when the wind was blowing east, which was the case 80 per cent of the time, it added.

Kahnawake is a Mohawk community on the South Shore of Montreal. The samples were taken in the eastern part of the community, close to the boundary with the town of Ste-Catherine and an industrial area that includes waste management plants.

The community’s high school, the Kahnawake Survival School, is less than a kilometre away from that industrial area.

The council is now working with Environment Canada for further tests and analysis.

Mylène Ratelle, professor at the Université de Montréal’s public health school, said these early results should raise concern, but not panic.

“It’s a yellow flag. It piques our interest, it draws our attention and tells us it would be worth looking into further,” said Ratelle, who was not involved in the analysis.

The lead levels presented by the council in the tests when the wind was blowing west are around 100 times higher than the average in areas that are away from industrial areas, said Ratelle.

She added that even if that high concentration was constant, it still would not be alarmingly high and its effects would mostly be felt in the long term.

“We consider that lead has no safe threshold … which means we should actively avoid being exposed to lead,” she said.

The proximity to the school was a particular point of concern, she said, as younger people are more vulnerable to the neurotoxic effects of lead.

“Especially for children, there is a risk of consequences on their health. Things like neurological system development, as well as cognitive (effects): memory issues, learning disorders, our ability to process and analyze information,” she said, adding that some studies have tied lead exposure to mood disorders.

Jason Calvert, operations manager for Kahnawake’s board of education, said the high school is planning on running more tests to see if its air filtration system is working as intended. For now, he said, the data is not cause for concern when it comes to students’ safety.

The data published by the council comes from seven tests conducted earlier this year for which samples were taken over three hours. This early data provides a snapshot rather than a full picture, said Ratelle. Lead concentration thresholds are calculated on average over a year.

Ultimately, more tests need to be run to evaluate whether lead concentrations present a danger to the community, she said.

“It would be important to look deeper if the concentration over a longer period stays similar, is lower or could even be a lot higher,” she said.

The council also said analysis of soil samples shows high levels of contamination on the eastern boundary of the community, though the soil on school ground is safe.

Kahnawake Grand Chief Cody Diabo said there have always been concerns about contamination in that area.

“The current boundaries of Kahnawake on almost all fronts are surrounded by industrial activities,” he said.

He said those concerns came back to the surface after media reported in January that the Terrapure waste management facility east of Kahnawake was facing accusations of dumping toxic water into the St. Lawrence Seaway.

Denis Beaulieu, Terrapure’s general manager, said the company will monitor the results of the additional testing.

“Terrapure takes environmental protection and community well-being seriously,” he said in an email. “Our facility employs air-quality control systems … to collect and treat emissions before discharge to the environment.”

Quebec’s environment ministry said reports on Terrapure’s atmospheric emissions for 2023 and 2024 showed the company was respecting provincial emissions limits.

Ratelle pointed out that it is still too early to determine the source of the lead in the air and soil. However, she said waste management facilities are known to emit heavy metals, including lead.

She added that the nearby road and gas station could contribute to lead emissions and that there also might be historical contamination in the area.

Diabo urged the government to change its environmental evaluations and emissions limit to better reflect the cumulative impact of areas with multiple industrial projects. He said that while every project individually might respect emissions thresholds, evaluations failed to consider pre-existing emissions in the area.

He encouraged the government to ensure development is done sustainably, both for people’s health and for the environment.

This report by The Canadian Press was first published Sept. 23, 2026.