According to the latest available data, 87 per cent of all arsenic emissions in Quebec come from the Horne Smelter in Rouyn-Noranda, in Abitibi-Témiscamingue.
RevolvAir, an organization dedicated to raising public awareness about air quality issues, has compiled data on arsenic emissions from industrial facilities in the province using the latest publicly available data from the National Pollutant Release Inventory (NPRI).
The results show that the Horne smelter is responsible for nearly all industrial arsenic emissions into the air in Quebec.
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Of the 16.3 metric tons of arsenic released by industries in 2024, 14 metric tons came from the Horne smelter—87 per cent.
The founder of the citizen-led initiative RevolvAir notes that arsenic emissions from the Horne smelter have been on the rise in recent years.
“If we round to the nearest whole number, it’s around 12 metric tons in 2023, 14 metric tons in 2024, and in 2025, the latest data indicates roughly 20 metric tons,” explained Guillaume Simard.
The foundry reported discharging 20 metric tons of arsenic in 2025—6 metric tons more than in 2024—but it is not yet known what proportion this represents of Quebec’s total, as not all data for 2025 has been made public yet.
Although emissions from the Horne smelter have been on the rise in recent years, Guillaume Simard notes that emissions from the company—which is owned by the multinational Glencore—have nonetheless decreased significantly over the past 30 years.
“In 2001, the smelter emitted 100 metric tons of arsenic,” notes Simard, who is also a teacher at Cégep de Sainte-Foy.
The Horne smelter is also the primary source of arsenic emissions in Canada.
Of the 33 metric tons of arsenic emitted by industrial facilities in Canada in 2024, 14 metric tons came from the Rouyn-Noranda smelter.
RevolvAir, an organization founded in 2022, develops smart air quality monitoring stations to measure, for example, fine particulate matter (PM2.5 and PM10) and CO2, thereby enabling schools, municipalities, and citizens to track changes in air quality in their local areas.
But the organization also compiles public data on air quality and works to make it more understandable for citizens.
“We take data from the National Pollutant Release Inventory, which can sometimes be a bit ‘dry’ and hard to understand,” and “we turn it into graphs” or “interactive maps,” explained Guillaume Simard, who has made it his mission to democratize access to environmental data.
“We should normally have the right to a healthy environment for our children. The more we reduce these air pollutants in the water and in the air, the better our health will be.”
In Quebec, air pollution is linked to 4,000 premature deaths per year, according to a 2021 Health Canada report. This results in costs of more than $30 billion per year for Quebec’s healthcare system, the report states.
–This report by La Presse Canadienne was translated by CityNews
