ROUYN-NORANDA, QC, March 26, 2026 /CNW/ - Inaccurate information about ambient air arsenic concentrations in Rouyn-Noranda is currently circulating in the public domain. Glencore Canada wishes to clarify key data and present an accurate picture of the situation.

Why the suggested 11% increase is misleading

Ambient air arsenic concentrations do not reflect smelter operations or emissions alone. They are also influenced by factors outside its control, such as weather conditions, wind patterns and seasonal variation.

Comparing equivalent time periods is therefore essential to drawing valid conclusions. The official annual average, as established by the Ministry of the Environment, is calculated from March 16 to March 15 of the following year, providing a stable basis for comparison.

The 11% increase cited publicly is based on a methodologically flawed comparison between a partial nine-month average (March 16 to December 29, 2025) and the full annual average for 2024 (March 16, 2024 to March 15, 2025).

"Rigorous data analysis is essential. Comparing a partial-year figure to an official annual average means putting non-equivalent values side by side. That kind of exercise creates unnecessary confusion. As we do every year, we will share the official annual average with the public once the validation process is complete," said Marie-Elise Viger, Environment Director, North American Copper Operations, Glencore.

Results below regulatory thresholds

Since 2023, the annual average arsenic concentration in ambient air measured at the Horne Smelter property boundary has remained below the ceilings set by the current ministerial authorization. Between 2022 and 2024, average arsenic concentrations measured at the Horne Smelter's official monitoring station decreased by 46.5%. In 2024, 99% of the urban area of Rouyn-Noranda recorded arsenic concentrations at or below 15 ng/m³.

Arsenic concentrations drop sharply with distance from the smelter. At the Glencore Arena, located approximately 400 metres away, the annual average concentration was 7.8 ng/m³ in 2024.

An environmental track record heading in the right direction

In environmental performance, long-term trends are the true measure of improvement. On that front, the picture is unambiguous: since 2005, the annual average arsenic concentration in ambient air at the official monitoring station has fallen by more than 70%.

"Today, our environmental performance for arsenic, cadmium and lead is already on par with European copper smelters recognized for best-in-class practices. The results of recent years reflect the tireless work and commitment of the teams. Glencore Canada is confident that the smelter's operations are safe for the people of Rouyn-Noranda. They were safe twenty years ago, when arsenic concentrations in the air were far higher than they are today," said Vincent Plante, General Manager, North American Copper, Glencore.

To learn more: http://www.glencore.ca

SOURCE Glencore Canada Corporation