Arsenic emissions increased at Horne Smelter in 2025

Fonderie Horne, a foundry owned by Glencore, is seen in Rouyn-Noranda, Que., on Oct. 29, 2022. (THE CANADIAN PRESS/Stephane Blais)

Arsenic emissions measured by the Horne Smelter in Rouyn-Noranda, Que. have increased over the past year, according to a report by the company, which is owned by multinational Glencore.

The average concentration of arsenic in the air in 2025, as measured by the smelter, reached an average of 40.9 nanograms (ng) per cubic metre (m³), according to data recorded at the Horne regulatory monitoring station in the Notre-Dame neighbourhood and published by the company on Tuesday.

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Last year’s report showed an average of 39.1 ng/m³; representing a 4.6 per cent increase over the course of a year.

“It is normal and expected that results may vary slightly from year to year due to several factors, including varying weather conditions like winds,” Glencore Canada wrote in a press release.

In a press release accompanying the results, the smelter noted that nearly all (96 per cent) of the Rouyn-Noranda urban area has ambient air arsenic concentrations of 15 ng/m³ or less, while the provincial standard has been 3 ng/m³ since 2011.

“I am proud of the work accomplished and the ongoing commitment of our teams,” said Vincent Plante, general manager of the Horne Smelter. ”We are convinced that operations at the Horne Smelter are safe for the public. They were safe 20 years ago when arsenic concentrations in the air were much higher, and they remain safe today.”

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However, Abitibi-Témiscamingue Public Health Director Omobola Sobanjo does not share Plante’s optimism, according to a letter sent in October 2025 to National Public Health Director Caroline Quach-Thanh.

“Considering the historically-recorded annual arsenic averages in the Notre-Dame neighbourhood, some residents of this neighborhood may have lived practically their entire lives in an environment where the carcinogenic risk level is considered unacceptable,” wrote Dr. Sobanjo.

13x the provincial standard

In the summer of 2022, a report by the Institut national de santé publique du Québec (INSPQ) revealed that, over a 70-year period, an excess number of Rouyn-Noranda residents — between one and 14 — would develop cancer if Glencore did not reduce the concentration of arsenic in the air emitted by the smelter.

Since 2022, the smelter has reduced arsenic emissions from 73 to 40.9 ng/m³.

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Despite these improvements, the concentration of arsenic in the air remained 13.6 times higher than the provincial standard in 2025.

It’s a situation deemed unacceptable by the group Mères au front de Rouyn-Noranda.

“No one wants people to lose their jobs. No one wants the smelter to close, but if the business model involves poisoning a population, we have to ask questions,” said Isabelle Fortin-Rondeau, a resident of Rouyn-Noranda and mother of two teenagers. “There is a problem.”

Special agreements

Although the annual standard set by the Clean Air Regulation is three nanograms (ng) per cubic metre (m³) for arsenic at plants built before 2011, over the years, the Horne Smelter, built in 1927, has benefited from special agreements with the government.

In the most recent ministerial authorization granted by Quebec in 2023, the smelter was required to meet a target of 45 ng/m³ by 2024 and 15 ng/m³ of arsenic starting at the end of 2027.

A few weeks ago, a bill amendment proposed granting new extensions to meet emission reduction targets for arsenic, as well as lead, cadmium, and other metals.

• READ MORE: Glencore Canada suspends major investments in its Horne Smelter

The current ministerial authorization, valid from 2023 to 2028, would be extended until 2033, despite warnings from the Regional Public Health Directorate, which stated last March that the government is underestimating “the real health risk in an environmental context unique to Quebec.”

As recently as last week, the Quebec Association of Physicians for the Environment (AQME) voiced support for the 118 doctors in Abitibi-Témiscamingue, who are calling on Quebec Premier Christine Fréchette to revoke the concessions granted to the Horne Smelter.

“We have a new premier, we have a new environment minister, so we want to encourage them to do better than their predecessors,” said Isabelle Fortin-Rondeau, spokesperson for Mères au front in Rouyn-Noranda, on Tuesday. “Otherwise, we find ourselves hoping that a future government not affiliated with the [Coalition Avenir Québec] CAQ would do better and finally take this issue in hand.”

‘Unattainable’ target

According to the most recent ministerial authorization, the smelter must not only meet a target of 45 ng/m³ by 2024 and comply with a target of 15 ng/m³ starting in 2027, but also submit an action plan to meet the Quebec standard.

• READ MORE: Horne Smelter: Legault ready to ensure ‘7 years of predictability’

Last July, the general manager of the Horne Smelter, Vincent Plante, stated that he believed this 3 ng/m³ standard was “technically impossible” to achieve.

This report by The Canadian Press was first published in French on April 29, 2026.