Current Problems


Sulphur dioxide levels off the charts in Ontario’s Chemical Valley

May 31, 2024

Children play outside the Aamjiwnaang First Nation Reserve school in Canada, across the U.S.-Canada border from Port Huron, Mich., Oct. 21, 2005. (AP Photo/Carlos Osorio) 


Goal: $100k



Canada’s National Observer: In the aftermath of a crackdown on benzene pollution plaguing Chemical Valley, environmental watchdogs say another chemical that causes choking, coughing and burning eyes and throats is still abundant.

Sulphur dioxide levels in the region, which is home to 67 petrochemical plants near Sarnia, have also been exceedingly high. Levels regularly exceed federal air quality standards despite new regulations passed by Ontario in 2022 aimed at reducing emissions by 90 per cent in the Sarnia area.

Sulphur dioxide is a toxic compound released in the refining of hydrogen sulphide, otherwise known as “sour gas,” recognized for its pungent rotten-egg smell. Much of the sour gas refined in the Chemical Valley comes from Alberta crude. It is released when plants flare and while processing the bottom of the crude at certain petrochemical plants in the region.

Sulphur dioxide can cause breathing difficulties for those suffering respiratory illnesses such as asthma and other diseases. Short-term exposure to high concentrations of sulphur dioxide can harm the respiratory system of humans and animals, with even greater risks for those with existing respiratory issues, according to the federal government.

Monitoring posted on social media for the Aamjiwnaang First Nation, which is nestled in the heart of Sarnia’s petrochemical industry, reveals that monthly spikes of sulphur dioxide continue at dangerous levels. In March and April alone, emissions were recorded above 150 parts per billion (ppb) for the maximum one-hour average, more than double the air quality standards set by Ottawa.

At the same time that benzene levels sent Aamjiwnaang citizens to hospital, sulphur dioxide levels spiked at 200 ppb. Currently, the federal government has set the Canadian Ambient Air Quality Standards for sulphur dioxide at 70 ppb peaks.

Sulphur dioxide mitigation measures were not included in a federal interim order issued this month to limit toxic benzene pollution from Sarnia’s petrochemical industry. However, it will be included in volatile organic compound draft regulations set to be released by Ottawa next February.

It is not known why this discrepancy exists, and Canada’s National Observer was not able to get immediate clarification from Environment and Climate Change Minister Steven Guilbeault’s office.

On Tuesday, Ottawa extended its interim order to mitigate benzene pollution in Sarnia’s petrochemical industry for two years. The benzene interim order issued by Guilbeault marks an unprecedented move by his office to mitigate air pollution, according to a spokesperson.

While applied to the petrochemical industry generally, the interim order on benzene is a direct response to INEOS Styrolution operating in Chemical Valley. Ontario suspended INEOS’s environmental compliance approval on May 1, requiring the company to cease accepting and storing benzene, investigate the source of leaks and conduct necessary repairs, amongst other measures.

INEOS is appealing the province’s decision, reported the CBC last week.

In a recent interview with Canada’s National Observer, Guilbeault said his department is trying to support what Ontario is doing to benefit communities.

“At the time when I spoke to [Ontario’s environment] minister, the company had threatened to take them to court for their emergency order, and I told her, ‘Well, if they want to take you to court, now they’ll have to take us to court as well,” he said.

INEOS did not return a request for comment by deadline.

Even though the plant is not operating at the moment, high benzene levels were recorded this week, prompting the band council to close several buildings on May 29 and 30. In April, benzene pollution from the region sent some Aamjiwnaang band members to hospital and forced closures of several buildings, including the band office and day care.

“Air pollution control requirements in the United States are significantly more effective and stringent than requirements in Canada,” reads the Aamjiwnaang air monitoring report. “One possible path forward is for the Aamjiwnaang Environment Department to be treated as an equal for all environmental protection activities and for the Canadian government to provide the necessary capacity funding.”

In a statement, Environment and Climate Change Canada said “many of the new requirements” for petrochemical facilities outlined in the interim order exist in other jurisdictions, such as the United States.

Additionally, the department “is working with the Aamjiwnaang First Nation to establish a partnership table to facilitate the co-development of solutions to the community’s long-standing concerns on pollution, including air quality.”

In Chemical Valley, sulphur dioxide can be released from acid gas flaring at refineries and petrochemical facilities. Failures in pollution control equipment and unscheduled shutdowns can also increase sulphur dioxide levels. To refine the sour fuel, petrochemical plants must remove and manage the hydrogen sulphide, which is itself toxic and explosive, explained Elaine MacDonald, Ecojustice’s program director of healthy communities.

Often, petrochemical plants manage the gas by turning the fuel into sulphuric acid or other compounds. However, when there are problems, petrochemical plants will sometimes burn sour gas through flaring, releasing sulphur dioxide, she adds. Flaring is when shots of toxic gas burn in the air like a lighter flame.

The compound can also react with other pollutants and develop into substances known as fine particulate matter, which has a diameter of 2.5 microns or smaller. Fine particulate matter, called PM2.5 for short, can significantly impact the health and well-being of almost everyone by getting into the lungs and affecting the cardiovascular system.

“Pollution can cause the air to smell like rotten eggs, and induce dizziness and nausea,” Chris Plain, Chief of Aamjiwnaang, told a senate committee on environmental racism last year.

“Residents face constant flaring noise, sirens and the occasional shelter in place, and physical and psychological health problems are common, including high rates of miscarriage, child asthma and cancer,” he added.

Ottawa’s interim order accelerates the forthcoming volatile organic compounds regulations, expected in February 2025, which were published in draft form in February 2024, Macdonald said.

For clean air advocates, the regulations are a vital step toward tackling toxic pollution.

Matteo Cimellaro and John Woodside / Canada’s National Observer / Local Journalism Initiative