Quebec's government is facing pressure to reduce arsenic levels in the air of a small northwestern city that is home to a copper foundry employing 650 people but emitting 33 times the provincewide standard of arsenic emissions.

A study released Wednesday by Quebec's public health institute said that if the factory in Rouyn-Noranda, Que., doesn't reduce the concentration of arsenic in its emissions, between one and 14 additional residents could develop cancer by the year 2060.

Public health director Dr. Luc Boileau visited the city Wednesday and told reporters, "We can't find it acceptable that a population is subject to this risk."

Boileau's visit came after the publication of an open letter earlier in the week by 50 health professionals urging Quebec to address the high level of air pollution in the city caused by the factory -- the Fonderie Horne -- which has been in operation since 1927. Boileau's visit also came as the factory's certification is set to expire and as the province begins negotiations with the company regarding a new emissions cap.

The factory has been in the spotlight in Quebec following a recent Radio-Canada report revealing that in July 2019, Dr. Horacio Arruda, then-director of public health, removed from a report an appendix mentioning how Rouyn-Noranda residents had higher rates of lung cancer compared with people in the rest of the province. The report cited arsenic in the air as a leading factor.

Arruda had allegedly removed the report after meeting with leaders of the foundry, owned by the multinational Glencore. He recently told reporters that he did nothing wrong and never intended to hide anything from the public.

The study released Wednesday by l'Institut national de sante publique du Quebec said that a rapid and major reduction in arsenic emissions would improve public health. "This is all the more relevant as arsenic … emissions contribute to soil contamination to which young children are particularly exposed," the report said.

Boileau, however, declined to say what an acceptable level of arsenic emissions would be, referring questions about standards to the Environment Department.

"If you ask me, today, if there are (arsenic levels) that justify saying we need to shut down the company and avoid all emissions starting today … the answer is no," Boileau said.

The provincial standard for arsenic emissions is three nanograms per cubic metre. The foundry's most recent cap, however, was set in 2018 at 100 ng per cubic metre.

Environment Minister Benoit Charette on Wednesday blamed former governments for the certification that allowed the foundry to exceed the provincewide standard. Glencore's certification for its factory in Rouyn-Noranda is coming to an end, and the Environment Department will have to negotiate a new agreement with the company, Charette told reporters in Quebec City.

"(The certification) … is under review every five years; it's the law," Charette said.

"It's the previous government that established the norms … it was respected; the foundry reduced (emissions) according to the requirements, but we agree that the requirements aren't enough."

Meanwhile, Quebec's college of physicians and the Long Point First Nation, located 80 kilometres south of Rouyn-Noranda, have added their voices to those calling on the government to reduce the levels of arsenic in the air around the factory.

"Considering that the (Fonderie Horne) has been emitting high levels of arsenic for decades … we have reason to be collectively concerned," Long Point Grand Chief Steeve Mathias said in a statement Wednesday.

In a tweet two days earlier, the college of physicians said the health of people living in Rouyn-Noranda was "vital."

"The science is clear," the group said. "Measures must be put in place quickly to ensure better air quality."

Premier Francois Legault on Tuesday suggested the factory could be shut down if it can't reduce emissions.

"Let's be very clear: if there's no proposed plan from the company to reduce the emissions to a level that is safe for the population, we do not rule out closing it," Legault said.

The premier said the immediate closure of the foundry would impact families, adding that he wanted to preserve the hundreds of "well-paying jobs" in the region.

Claude Belanger, a spokesman for Glencore, said in a news release Wednesday that the foundry has a "concrete plan to further reduce its emissions" and that it is determined to "improve the situation."

The company said it was "finalizing the development of a transition zone" to reduce arsenic exposure to citizens. It added that it is also developing copper-treatment processes "unique in the world, which will allow optimal capture of gases and dust."

As well, Glencore said the foundry will "act in full collaboration with government and public health authorities."

- This report by The Canadian Press was first published on July 6, 2022. This story was produced with the financial assistance of the Meta and Canadian Press News Fellowship.