Clean Air. Everywhere.
Ontario’s current air pollution control framework fails to protect human health, particularly in under-resourced and underrepresented communities. The system relies on outdated standards, broad exemptions, and narrow assessment tools that ignore the cumulative impacts faced by communities living near multiple industrial sources. As a result, the highest exposures occur in places with the least resources to mitigate or challenge these risks. To ensure meaningful and equitable protection, Ontario must overhaul its regulatory regime to consider the cumulative impacts of air pollution on nearby communities, close loopholes, and modernize standards that reflect the real conditions experienced by disproportionately affected communities.
Next Page
Air Pollution in Focus: How These 5 Ontario Communities are at Risk
Sudbury
Sault Ste. Marie
Underrepresented and under-resourced groups are disproportionately harmed by air pollution and the environmental threats it carries. This is especially true of the communities in and around Ontario's industrial hubs, with facilities sometimes permitted to emit airborne contaminants thousands of times higher than Ontario's provincial standards and little consideration given to the cumulative impacts. Concentrated levels of air pollution in these areas leads to a higher incidence of respiratory and cardiovascular illness, highlighting the need for stronger restrictions and protective policies to ensure environmental justice. We have chosen to highlight how cumulative air pollution is unfairly impacting four industrial regions in Ontario.
Hamilton
Aamjiwnaang First Nation/Sarnia
- Aamjiwnaang First Nation and Sarnia
- Hamilton
- Sault Ste. Marie
- Sudbury
Click on the red points to get started!
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Aamjiwnaang First Nation + Sarnia
Community Snapshot
Aamjiwnaang First Nation population: ~2500 Sarnia population: ~72000 Both communities are bordered by Sarnia’s “Chemical Valley” – over 60 chemical plants and refineries in the area. The communities’ experience is intertwined with the industry’s benefits and burdens. Residents enjoy employment and infrastructure from industry, yet they spend their entire lives in disproportionate exposure to air pollution. This raises an issue of environmental justice, as Aamjiwnaang First Nation members and low-income Sarnians bear a disproportionate pollution load with their proximity to industrial emitters.
Back
Pollution Sources
Aamjiwnaang First Nation + Sarnia
Pollution Sources
The petrochemical and refining industries are primarily responsible for the degraded air quality in the Aamjiwnaang First Nation and Sarnia regions. Local petrochemical and refining industries regularly release volatile organic compounds, sulphur dioxide, nitrogen oxides, and fine particulate matter. In 2024, benzene levels near Aamjiwnaang First Nation were measured to be more than 300 times higher than the provincial standard for annual benzene emissions. The Ontario government historically allowed such high emissions through lenient technical standards and site-specific standards.
Back
Cumulative Effects
Aamjiwnaang First Nation + Sarnia
Cumulative Exposure
The 60 chemical plants and refineries in Chemical Valley are each individually permitted to release different pollutants into the atmosphere. The cumulative mix of these pollutants - which may be much more than what any individual plant is allowed to release - is what people in Aamjiwnaang First Nation and Sarnia are exposed to throughout their lives. Under certain weather conditions, this combined burden can further degrade local air quality through the interaction of various pollutants (e.g. benzene, sulfur dioxide, particulates). Temperature inversions or still air can trap a chemical soup over the area, exposing residents to even greater harm. Additionally, smog from US facilities in the St. Clair River corridor can get blown across the border, adding to the regional levels of ozone and fine particulate matter in the area. Considering the Ontario government’s system, which regulates each facility on its own, the combined impact from multiple sources is neglected to the detriment of the people these systems are supposed to protect.
Back
Concerns and Impacts
Aamjiwnaang First Nation + Sarnia
Concerns and Impacts
The Ontario Ministry of the Environment, Conservation and Parks (MECP) published a study in 2024, which found that sulfur dioxide, fine particulate matter, and benzene are responsible for elevated health risks in the broader Sarnia area. Benzene is linked to higher risks of cancer, and the north end of Aamjiwnaang First Nation showed the highest estimated lifetime cancer risk from air pollution in the region. Community members also report high rates of respiratory issues such as asthma, with frequent “shelter-in-place” incidents and odour/flare events. Air pollution in the Aamjiwnaang First Nation and Sarnia regions might not always be visible in the sky, but it is present in the form of colourless airborne chemicals, which can have distinct odours.
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Regulatory Gaps
Aamjiwnaang First Nation + Sarnia
Regulatory Gaps
The Ontario government had known for several years about the elevated risks associated with benzene inhalation, but chose not to take action until 2024, when Aamjiwnaang First Nation declared a state of emergency due to dangerously high levels of the substance in local air. In May 2024, the Government of Canada issued an Order in Council to address high levels of benzene from petrochemical facilities in the Sarnia area. Many of the plants in Chemical Valley have been approved for site-specific standards and technical standards, providing loopholes that legally permit them to exceed provincial limits. This regulatory framework fails to protect fence-line communities from multiple-source pollution and excludes these very communities from having a say in the decision-making process.
Back
Remedies and Solutions
Aamjiwnaang First Nation + Sarnia
Remedies and Solutions
New, stronger, and more holistic measures are required to reduce air pollution in Sarnia and protect its residents. Regulators should consider the total pollution burden placed on vulnerable communities, rather than the isolated impact of per facility. There must be regularly scheduled cumulative impact assessments for air pollution “hotspots” such as the Aamjiwnaang First Nation/Sarnia Region. The duration of each facility’s site-specific standard is around 5 to 10 years; reducing it to 2 to 3 years will close this loophole and allow for increased public participation and government accountability, as the MECP's proposals to grant a site-specific standard are posted on the Environmental Registry of Ontario, which the public can comment on.
Hamilton
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Hamilton
Community Snapshot
Population: 569,000. Located in southern Ontario, Hamilton's economy was built on heavy industry, notably two integrated steel mills and associated metal-processing plants alongside other manufacturing and transportation sectors. In recent decades, Hamilton’s local economy has diversified, but the east end of the city remains an industrial core. Air pollution concerns in Hamilton date back to the mid-20th century, when steel mill emissions and coal-fired power contributed to intense smog. Today, Hamilton enjoys generally better air quality than decades ago, but neighbourhoods near the steel facilities and highway corridors still experience chronically high air pollution levels. This poor air can disperse to lower-altitude parts of the city and remain trapped by the Escarpment, creating health disparities and raising environmental justice concerns that must be addressed.
Back
Pollution Sources
Hamilton
Pollution Sources
Hamilton deals with a mix of industrial emissions and transportation, with industry being historically dominant: steel mills, coke ovens, sintering, and finishing mills. Main pollutants: particulate matter (including metals), benzene, hydrocarbons, sulphur dioxide from coke and iron ore processing, nitrogen oxides. Heavy truck and rail traffic also produce diesel exhaust, and Hamilton sometimes receives regional smog blowing in from the U.S. and the Toronto area. Historically, Hamilton’s steel plants were granted site-specific air standards for carcinogens: allowed annual benzene concentrations about 8.7 times the normal provincial standard (3.9 µg/m³ vs 0.45 µg/m³), and elevated allowances for benzo[a]pyrene and particulate matter as well.
Cumulative Effects
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Hamilton
Cumulative Exposure
The cumulative exposure observed in Hamilton comes from the combination of industrial and urban sources. For instance, the North End neighbourhood is adjacent to two steel plants. The cumulative effects of this exposure can be specifically attributed to coke oven benzene emissions, blast furnace dust, and automotive exhaust from the nearby Highway 403 and the Queen Elizabeth Way. Although each source may remain within its approved emissions limits, the overlap between polluters results in overall higher exposure for residents. Ontario’s facility-by-facility approach to emissions regulation thus fails to consider how all of these factors, together, expose the city to unsafe levels of air pollution and an increased risk of respiratory illness.
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Concerns and Impacts
Hamilton
Concerns and Impacts
Despite notable reductions in Hamilton’s emissions in recent years, residents who live near the port and steel mills are still disproportionately exposed to airborne contaminants. The North and East End neighbourhoods report above-average rates of hospitalizations for asthma and Chronic Obstructive Pulmonary Disease (COPD). Odour and noise from industry also affect the quality of life. The city has conducted studies estimating that improving air quality could prevent dozens of premature deaths annually in Hamilton, highlighting that even current pollution levels have a tangible health cost. Although Hamiltonians recognize the progress that has been made in relation to cleaner air, vulnerable communities within the city are still subjected to an unfair burden. This underscores the environmental injustice still present within the city of Hamilton
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Regulatory Gaps
Hamilton
Regulatory Gaps
The individual, per-facility approvals fail to consider the combined effects of each facility’s emissions. This is a major flaw in the province’s pollution control system, exposing Hamilton’s residents to dangerous levels of pollutants known to harm human health. The Ontario government has also repeatedly granted Hamilton’s steel plants extensions and exemptions from the regulations meant to protect local communities. For example, when the new benzene and benzo[a]pyrene standards came into force in 2016, the steel mills were not ready to comply, so the province approved special standards for benzene (exceeding the general limits nearly ninefold), benzo[a]pyrene, and suspended particulate matter. The government then extended those approvals through at least 2023.
Back
Remedies and Solutions
Hamilton
Remedies and Solutions
Hamilton stands at a turning point where major industrial change and a new provincial policy approach could significantly improve air quality. Several key steps are needed to reduce air pollution in Hamilton and protect the city’s residents. Hamilton would benefit from adopting a cumulative effects framework through a regional air zone management approach under Ontario’s Air Quality Management System. This could set overall emission caps for the city’s industry hub. Enhanced fenceline and community monitoring should be implemented, with data made fully public and in real-time. Another step towards increased protection and reduced pollution involves the modernization of industrial processes, which includes both major steel plants transitioning to cleaner technology (ie, electric arc furnaces, improved coke oven emission capture) on an accelerated timeline. This process is already underway for one of the plants with federal-provincial funding, and the second plant must follow suit, or at least implement similar pollution controls. Government oversight must continue during such phases–enforcing standards and ensuring that green transitions are completed on time. A new approach to regulate and eliminate the gap between provincial standards and actual emissions is necessary. A firm end-date for exemptive loopholes must be in place, with ambitious emissions reduction goals for the steel industry to continuously lower benzene, PAH, and particulate emissions.
Sault Ste. Marie
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Sault Ste. Marie
Community Snapshot
Sault Ste. Marie has a population of approximately 76,000 people, located on the St. Marys River across from its twin city in Michigan. Traditionally a steel-manufacturing town, it hosts one of Canada’s largest integrated steel mills, along with a history of forestry and shipping industries. As a result, local air quality has been poor for decades. There are also two First Nation communities (Batchewana and Garden River), and rural areas that can be affected by industrial plumes. The legacy of the steel industry looms large in environmental discussions, and residents often note the contrast between the region’s natural beauty and the pollution from steelworks on the waterfront.
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Pollution Sources
Sault Ste. Marie
Pollution Sources
Sault Ste. Marie’s dominant source of air pollution is the integrated steel plant by the river. This plant includes coke ovens, blast furnaces, and basic oxygen furnaces. Pollution from Michigan’s same-named city also enters Sault Ste. Marie’s skies, adding to the pollutants that residents are exposed to. Main pollutants: particulate matter, benzene from coke oven gas, hydrocarbons from coal processing, sulphur dioxide and nitrogen oxides from combustion processes. The Ontario Government has approved site-specific air standards, exempting the steel operations from the provincial air quality standard and permitting benzene concentrations about 5 times higher than this standard. The plant is currently undergoing a transition to an electric arc furnace with an accelerated timeline due to ongoing trade tensions between Canada and the United States. This transition, however, has led to 1000 layoffs, posing a challenge for locals who rely on the steel industry for employment.
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Cumulative Effects
Sault Ste. Marie
Cumulative Exposure
Although Sault Ste. Marie only houses one major steel complex, cumulative air pollution exposure rises from the multiple chemical processes within the plant, emitting various pollutants. The provincial government’s system of regulating each pollutant on an individual basis fails to account for the accumulation of various pollutants in the air. This combination can create a synergistic effect, where multiple pollutants cause greater harm together than each would alone.
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Conerns and Impacts
Sault Ste. Marie
Concerns and Impacts
The individual, per-facility approvals fail to consider the combined effects of each facility’s emissions. This is a major flaw in the province’s pollution control system, exposing Hamilton’s residents to dangerous levels of pollutants known to harm human health. The Ontario government has also repeatedly granted Hamilton’s steel plants extensions and exemptions from the regulations meant to protect local communities. For example, when the new benzene and benzo[a]pyrene standards came into force in 2016, the steel mills were not ready to comply, so the province approved special standards for benzene (exceeding the general limits nearly ninefold), benzo[a]pyrene, and suspended particulate matter. The government then extended those approvals through at least 2023.
Back
Regulatory Gaps
Sault Ste. Marie
Regulatory Gaps
Weaknesses in policy and policy enforcement have historically allowed pollution to persist in Sault Ste. Marie. The steel plant has site-specific air standards for carcinogens like benzene and benzo[a]pyrene, and for particulate matter, meaning it is legally permitted to exceed normal provincial limits for these pollutants. Despite these leniencies, government regulators have not always enforced the reduced standards strictly. The plant has routinely violated even its site-specific standards. There is no cumulative impact framework; the approval process considers each pollutant individually, rather than considering the combined risk of multiple contaminants affecting residents at the same time.
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Remedies and Solutions
Sault Ste. Marie
Remedies and Solutions
Protecting community health in Sault Ste. Marie requires the province to shift from piecemeal, facility-by-facility regulation to a cumulative impact model that accounts for the combined emissions of the entire steelmaking complex and surrounding sources. The individual, per-facility approvals fail to consider the combined effects of each facility’s emissions. This is a major flaw in the province’s pollution control system, exposing Hamilton’s residents to dangerous levels of pollutants known to harm human health. The Ontario government has also repeatedly granted Hamilton’s steel plants extensions and exemptions from the regulations meant to protect local communities. For example, when the new benzene and benzo[a]pyrene standards came into force in 2016, the steel mills were not ready to comply, so the province approved special standards for benzene (exceeding the general limits nearly ninefold), benzo[a]pyrene, and suspended particulate matter. The government then extended those approvals through at least 2023.
Sudbury
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Sudbury
Community Snapshot
Sudbury is northern Ontario’s largest city, with a population of 166,000 people as of 2021. This city is a prominent mining and smelting center, with a continuing legacy of nickel and copper production. By the late 20th century, Sudbury’s vicinity had been severely deforested and tainted by pollution, though major efforts have since restored much of the local greenery. As a mineral-rich area, Sudbury contains several mining operations along with two smelters still active. Local air quality has moderately improved in recent years, but the communities closest to the smelter sites have historically endured the worst air quality.
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Pollution Sources
Sudbury
Pollution Sources
Smelting operations in Sudbury roast and smelt nickel-copper ore, emitting large quantities of sulphur dioxide and dust containing metals like nickel, copper, cobalt, lead, and arsenic. Emissions from furnace stacks and converters also carry toxic metals. This has historically led to contaminated soil in the region. Other local sources include mine operations, which create diesel exhaust and dust from rock crushing/tailing piles. The province has updated air standards for pollutants like nickel in dust–a new annual standard of 0.04 µg/m³ for nickel came into effect in 2023. However, the smelters cannot meet it yet. This led the government to propose a special industry rule exempting Sudbury smelters from the strict limit while they optimize controls–another example of a loophole that endangers locals' respiratory health.
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Cumulative Effects
Sudbury
Cumulative Exposure
With two main smelters and several mining sites, the heavy industrial presence in Sudbury results in cumulative impacts on the region’s air quality. Neighbourhoods nestled around and between the smelters are often breathing air polluted by both facilities. Sulfur dioxide emitted from both facilities also has the potential to create acidic conditions in downwind lakes, posing a risk to communities and ecosystems that rely on the lakes. This problem is intensified when emissions from both facilities are simultaneously released into the air. Moreover, legacy industrial sites (old roast beds, slag piles) still emit dust on dry windy days, adding to cumulative particulates. Sudbury’s mix of ongoing operations and historical pollution that contributes to current exposure results in unhealthy cumulative exposure for the area’s residents.
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Concerns and Impacts
Sudbury
Concerns and Impacts
Historically, the sulfur dioxide emissions in Sudbury have wiped out hundreds of hectares of vegetation in the area and acidified hundreds of lakes. Major liming and tree-planting efforts have since reversed much of this damage; however, the effects of sulfur dioxide exposure on human health can only be mitigated, but not fully undone. This is especially the case with older residents who were exposed to airborne pollutants when emissions were at their peak in years and decades past. In addition to the respiratory health risks posed by sulfur dioxide, the Canadian Centre for Occupational Health and Safety classifies it as a Category 2 germ cell mutagen, meaning that it can lead to genetic damage if chronically inhaled.
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Regulatory Gaps
Sudbury
Regulatory Gaps
As the Ontario government tightened air standards for contaminants like nickel and SO2, they recognized that the smelting and refinery operations will not meet the new standards by the deadline; the MECP thus proposed to exempt the facilities from more stringent standards. This approach creates a loophole where Sudbury’s residents are not protected by the same health-conscious limits that apply in other regions across Ontario. Another gap lies in how legacy contamination is addressed: air regulations cover emissions, but not the historically polluted soils that can still release dust. Cleanup of those falls under other frameworks, which are often slow and resource-intensive.
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Polution Sources
Sudbury
Remedies and Solutions
Sudbury’s continued environmental recovery depends on the province adopting a system that evaluates pollution from multiple smelters and legacy sources together, rather than regulating each emitter in isolation. Companies must be required to demonstrate continuous progress toward the stringent SO2 limits, and if technical or economic barriers exist, the provincial and federal governments could support technology upgrades in a way similar to that seen in Sault Ste. Marie. Augmenting the air monitoring network is also needed: more continuous monitors (for SO₂ and fine particulates) in communities like Copper Cliff, Lively, and Falconbridge, with data available online for residents to see current air quality. Cumulative effects measurements should be formally introduced. For example, an annual review that combines emissions data from both major smelters, plus mines, to evaluate the total pollution load on Sudbury’s population and ecosystem. This could inform if further regulatory actions are necessary. Addressing legacy pollution is also part of the air quality picture; continued soil remediation and dust control at contaminated sites will reduce the resuspension of toxic particles. Sudbury’s re-greening program should persist, as vegetation cover helps trap dust and improve air quality.
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Sault Ste. Marie
Community Snapshot
Sault Ste. Marie has a population of approximately 76,000 people, located on the St. Marys River across from its twin city in Michigan. Traditionally a steel-manufacturing town, it hosts one of Canada’s largest integrated steel mills, along with a history of forestry and shipping industries. As a result, local air quality has been poor for decades. There are also two First Nation communities (Batchewana and Garden River), and rural areas that can be affected by industrial plumes. The legacy of the steel industry looms large in environmental discussions, and residents often note the contrast between the region’s natural beauty and the pollution from steelworks on the waterfront.
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Polution Sources
Aamjiwnaang First Nation + Sarnia
Community Snapshot
Aamjiwnaang First Nation population: ~2500 Sarnia population: ~72000 Both communities are bordered by Sarnia’s “Chemical Valley” – over 60 chemical plants and refineries in the area. The communities’ experience is intertwined with the industry’s benefits and burdens. Residents enjoy employment and infrastructure from industry, yet they spend their entire lives in disproportionate exposure to air pollution. This raises an issue of environmental justice, as Aamjiwnaang First Nation members and low-income Sarnians bear a disproportionate pollution load with their proximity to industrial emitters.
Return to Home
Pollution Sources
Sudbury
Community Snapshot
Sudbury is northern Ontario’s largest city, with a population of 166,000 people as of 2021. This city is a prominent mining and smelting center, with a continuing legacy of nickel and copper production. By the late 20th century, Sudbury’s vicinity had been severely deforested and tainted by pollution, though major efforts have since restored much of the local greenery. As a mineral-rich area, Sudbury contains several mining operations along with two smelters still active. Local air quality has moderately improved in recent years, but the communities closest to the smelter sites have historically endured the worst air quality.
Return to Home
Polution Sources
Hamilton
Community Snapshot
Population: 569,000. Located in southern Ontario, Hamilton's economy was built on heavy industry, notably two integrated steel mills and associated metal-processing plants alongside other manufacturing and transportation sectors. In recent decades, Hamilton’s local economy has diversified, but the east end of the city remains an industrial core. Air pollution concerns in Hamilton date back to the mid-20th century, when steel mill emissions and coal-fired power contributed to intense smog. Today, Hamilton enjoys generally better air quality than decades ago, but neighbourhoods near the steel facilities and highway corridors still experience chronically high air pollution levels. This poor air can disperse to lower-altitude parts of the city and remain trapped by the Escarpment, creating health disparities and raising environmental justice concerns that must be addressed.
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Pollution Sources
Air Pollution Community Profiles
Canadian Environmental Law Association
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Transcript
Clean Air. Everywhere.
Ontario’s current air pollution control framework fails to protect human health, particularly in under-resourced and underrepresented communities. The system relies on outdated standards, broad exemptions, and narrow assessment tools that ignore the cumulative impacts faced by communities living near multiple industrial sources. As a result, the highest exposures occur in places with the least resources to mitigate or challenge these risks. To ensure meaningful and equitable protection, Ontario must overhaul its regulatory regime to consider the cumulative impacts of air pollution on nearby communities, close loopholes, and modernize standards that reflect the real conditions experienced by disproportionately affected communities.
Next Page
Air Pollution in Focus: How These 5 Ontario Communities are at Risk
Sudbury
Sault Ste. Marie
Underrepresented and under-resourced groups are disproportionately harmed by air pollution and the environmental threats it carries. This is especially true of the communities in and around Ontario's industrial hubs, with facilities sometimes permitted to emit airborne contaminants thousands of times higher than Ontario's provincial standards and little consideration given to the cumulative impacts. Concentrated levels of air pollution in these areas leads to a higher incidence of respiratory and cardiovascular illness, highlighting the need for stronger restrictions and protective policies to ensure environmental justice. We have chosen to highlight how cumulative air pollution is unfairly impacting four industrial regions in Ontario.
Hamilton
Aamjiwnaang First Nation/Sarnia
Click on the red points to get started!
Back
Aamjiwnaang First Nation + Sarnia
Community Snapshot
Aamjiwnaang First Nation population: ~2500 Sarnia population: ~72000 Both communities are bordered by Sarnia’s “Chemical Valley” – over 60 chemical plants and refineries in the area. The communities’ experience is intertwined with the industry’s benefits and burdens. Residents enjoy employment and infrastructure from industry, yet they spend their entire lives in disproportionate exposure to air pollution. This raises an issue of environmental justice, as Aamjiwnaang First Nation members and low-income Sarnians bear a disproportionate pollution load with their proximity to industrial emitters.
Back
Pollution Sources
Aamjiwnaang First Nation + Sarnia
Pollution Sources
The petrochemical and refining industries are primarily responsible for the degraded air quality in the Aamjiwnaang First Nation and Sarnia regions. Local petrochemical and refining industries regularly release volatile organic compounds, sulphur dioxide, nitrogen oxides, and fine particulate matter. In 2024, benzene levels near Aamjiwnaang First Nation were measured to be more than 300 times higher than the provincial standard for annual benzene emissions. The Ontario government historically allowed such high emissions through lenient technical standards and site-specific standards.
Back
Cumulative Effects
Aamjiwnaang First Nation + Sarnia
Cumulative Exposure
The 60 chemical plants and refineries in Chemical Valley are each individually permitted to release different pollutants into the atmosphere. The cumulative mix of these pollutants - which may be much more than what any individual plant is allowed to release - is what people in Aamjiwnaang First Nation and Sarnia are exposed to throughout their lives. Under certain weather conditions, this combined burden can further degrade local air quality through the interaction of various pollutants (e.g. benzene, sulfur dioxide, particulates). Temperature inversions or still air can trap a chemical soup over the area, exposing residents to even greater harm. Additionally, smog from US facilities in the St. Clair River corridor can get blown across the border, adding to the regional levels of ozone and fine particulate matter in the area. Considering the Ontario government’s system, which regulates each facility on its own, the combined impact from multiple sources is neglected to the detriment of the people these systems are supposed to protect.
Back
Concerns and Impacts
Aamjiwnaang First Nation + Sarnia
Concerns and Impacts
The Ontario Ministry of the Environment, Conservation and Parks (MECP) published a study in 2024, which found that sulfur dioxide, fine particulate matter, and benzene are responsible for elevated health risks in the broader Sarnia area. Benzene is linked to higher risks of cancer, and the north end of Aamjiwnaang First Nation showed the highest estimated lifetime cancer risk from air pollution in the region. Community members also report high rates of respiratory issues such as asthma, with frequent “shelter-in-place” incidents and odour/flare events. Air pollution in the Aamjiwnaang First Nation and Sarnia regions might not always be visible in the sky, but it is present in the form of colourless airborne chemicals, which can have distinct odours.
Back
Regulatory Gaps
Aamjiwnaang First Nation + Sarnia
Regulatory Gaps
The Ontario government had known for several years about the elevated risks associated with benzene inhalation, but chose not to take action until 2024, when Aamjiwnaang First Nation declared a state of emergency due to dangerously high levels of the substance in local air. In May 2024, the Government of Canada issued an Order in Council to address high levels of benzene from petrochemical facilities in the Sarnia area. Many of the plants in Chemical Valley have been approved for site-specific standards and technical standards, providing loopholes that legally permit them to exceed provincial limits. This regulatory framework fails to protect fence-line communities from multiple-source pollution and excludes these very communities from having a say in the decision-making process.
Back
Remedies and Solutions
Aamjiwnaang First Nation + Sarnia
Remedies and Solutions
New, stronger, and more holistic measures are required to reduce air pollution in Sarnia and protect its residents. Regulators should consider the total pollution burden placed on vulnerable communities, rather than the isolated impact of per facility. There must be regularly scheduled cumulative impact assessments for air pollution “hotspots” such as the Aamjiwnaang First Nation/Sarnia Region. The duration of each facility’s site-specific standard is around 5 to 10 years; reducing it to 2 to 3 years will close this loophole and allow for increased public participation and government accountability, as the MECP's proposals to grant a site-specific standard are posted on the Environmental Registry of Ontario, which the public can comment on.
Hamilton
Back
Return to Launchpad
Hamilton
Community Snapshot
Population: 569,000. Located in southern Ontario, Hamilton's economy was built on heavy industry, notably two integrated steel mills and associated metal-processing plants alongside other manufacturing and transportation sectors. In recent decades, Hamilton’s local economy has diversified, but the east end of the city remains an industrial core. Air pollution concerns in Hamilton date back to the mid-20th century, when steel mill emissions and coal-fired power contributed to intense smog. Today, Hamilton enjoys generally better air quality than decades ago, but neighbourhoods near the steel facilities and highway corridors still experience chronically high air pollution levels. This poor air can disperse to lower-altitude parts of the city and remain trapped by the Escarpment, creating health disparities and raising environmental justice concerns that must be addressed.
Back
Pollution Sources
Hamilton
Pollution Sources
Hamilton deals with a mix of industrial emissions and transportation, with industry being historically dominant: steel mills, coke ovens, sintering, and finishing mills. Main pollutants: particulate matter (including metals), benzene, hydrocarbons, sulphur dioxide from coke and iron ore processing, nitrogen oxides. Heavy truck and rail traffic also produce diesel exhaust, and Hamilton sometimes receives regional smog blowing in from the U.S. and the Toronto area. Historically, Hamilton’s steel plants were granted site-specific air standards for carcinogens: allowed annual benzene concentrations about 8.7 times the normal provincial standard (3.9 µg/m³ vs 0.45 µg/m³), and elevated allowances for benzo[a]pyrene and particulate matter as well.
Cumulative Effects
Back
Hamilton
Cumulative Exposure
The cumulative exposure observed in Hamilton comes from the combination of industrial and urban sources. For instance, the North End neighbourhood is adjacent to two steel plants. The cumulative effects of this exposure can be specifically attributed to coke oven benzene emissions, blast furnace dust, and automotive exhaust from the nearby Highway 403 and the Queen Elizabeth Way. Although each source may remain within its approved emissions limits, the overlap between polluters results in overall higher exposure for residents. Ontario’s facility-by-facility approach to emissions regulation thus fails to consider how all of these factors, together, expose the city to unsafe levels of air pollution and an increased risk of respiratory illness.
Back
Concerns and Impacts
Hamilton
Concerns and Impacts
Despite notable reductions in Hamilton’s emissions in recent years, residents who live near the port and steel mills are still disproportionately exposed to airborne contaminants. The North and East End neighbourhoods report above-average rates of hospitalizations for asthma and Chronic Obstructive Pulmonary Disease (COPD). Odour and noise from industry also affect the quality of life. The city has conducted studies estimating that improving air quality could prevent dozens of premature deaths annually in Hamilton, highlighting that even current pollution levels have a tangible health cost. Although Hamiltonians recognize the progress that has been made in relation to cleaner air, vulnerable communities within the city are still subjected to an unfair burden. This underscores the environmental injustice still present within the city of Hamilton
Back
Regulatory Gaps
Hamilton
Regulatory Gaps
The individual, per-facility approvals fail to consider the combined effects of each facility’s emissions. This is a major flaw in the province’s pollution control system, exposing Hamilton’s residents to dangerous levels of pollutants known to harm human health. The Ontario government has also repeatedly granted Hamilton’s steel plants extensions and exemptions from the regulations meant to protect local communities. For example, when the new benzene and benzo[a]pyrene standards came into force in 2016, the steel mills were not ready to comply, so the province approved special standards for benzene (exceeding the general limits nearly ninefold), benzo[a]pyrene, and suspended particulate matter. The government then extended those approvals through at least 2023.
Back
Remedies and Solutions
Hamilton
Remedies and Solutions
Hamilton stands at a turning point where major industrial change and a new provincial policy approach could significantly improve air quality. Several key steps are needed to reduce air pollution in Hamilton and protect the city’s residents. Hamilton would benefit from adopting a cumulative effects framework through a regional air zone management approach under Ontario’s Air Quality Management System. This could set overall emission caps for the city’s industry hub. Enhanced fenceline and community monitoring should be implemented, with data made fully public and in real-time. Another step towards increased protection and reduced pollution involves the modernization of industrial processes, which includes both major steel plants transitioning to cleaner technology (ie, electric arc furnaces, improved coke oven emission capture) on an accelerated timeline. This process is already underway for one of the plants with federal-provincial funding, and the second plant must follow suit, or at least implement similar pollution controls. Government oversight must continue during such phases–enforcing standards and ensuring that green transitions are completed on time. A new approach to regulate and eliminate the gap between provincial standards and actual emissions is necessary. A firm end-date for exemptive loopholes must be in place, with ambitious emissions reduction goals for the steel industry to continuously lower benzene, PAH, and particulate emissions.
Sault Ste. Marie
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Return to Launchpad
Sault Ste. Marie
Community Snapshot
Sault Ste. Marie has a population of approximately 76,000 people, located on the St. Marys River across from its twin city in Michigan. Traditionally a steel-manufacturing town, it hosts one of Canada’s largest integrated steel mills, along with a history of forestry and shipping industries. As a result, local air quality has been poor for decades. There are also two First Nation communities (Batchewana and Garden River), and rural areas that can be affected by industrial plumes. The legacy of the steel industry looms large in environmental discussions, and residents often note the contrast between the region’s natural beauty and the pollution from steelworks on the waterfront.
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Pollution Sources
Sault Ste. Marie
Pollution Sources
Sault Ste. Marie’s dominant source of air pollution is the integrated steel plant by the river. This plant includes coke ovens, blast furnaces, and basic oxygen furnaces. Pollution from Michigan’s same-named city also enters Sault Ste. Marie’s skies, adding to the pollutants that residents are exposed to. Main pollutants: particulate matter, benzene from coke oven gas, hydrocarbons from coal processing, sulphur dioxide and nitrogen oxides from combustion processes. The Ontario Government has approved site-specific air standards, exempting the steel operations from the provincial air quality standard and permitting benzene concentrations about 5 times higher than this standard. The plant is currently undergoing a transition to an electric arc furnace with an accelerated timeline due to ongoing trade tensions between Canada and the United States. This transition, however, has led to 1000 layoffs, posing a challenge for locals who rely on the steel industry for employment.
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Cumulative Effects
Sault Ste. Marie
Cumulative Exposure
Although Sault Ste. Marie only houses one major steel complex, cumulative air pollution exposure rises from the multiple chemical processes within the plant, emitting various pollutants. The provincial government’s system of regulating each pollutant on an individual basis fails to account for the accumulation of various pollutants in the air. This combination can create a synergistic effect, where multiple pollutants cause greater harm together than each would alone.
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Conerns and Impacts
Sault Ste. Marie
Concerns and Impacts
The individual, per-facility approvals fail to consider the combined effects of each facility’s emissions. This is a major flaw in the province’s pollution control system, exposing Hamilton’s residents to dangerous levels of pollutants known to harm human health. The Ontario government has also repeatedly granted Hamilton’s steel plants extensions and exemptions from the regulations meant to protect local communities. For example, when the new benzene and benzo[a]pyrene standards came into force in 2016, the steel mills were not ready to comply, so the province approved special standards for benzene (exceeding the general limits nearly ninefold), benzo[a]pyrene, and suspended particulate matter. The government then extended those approvals through at least 2023.
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Regulatory Gaps
Sault Ste. Marie
Regulatory Gaps
Weaknesses in policy and policy enforcement have historically allowed pollution to persist in Sault Ste. Marie. The steel plant has site-specific air standards for carcinogens like benzene and benzo[a]pyrene, and for particulate matter, meaning it is legally permitted to exceed normal provincial limits for these pollutants. Despite these leniencies, government regulators have not always enforced the reduced standards strictly. The plant has routinely violated even its site-specific standards. There is no cumulative impact framework; the approval process considers each pollutant individually, rather than considering the combined risk of multiple contaminants affecting residents at the same time.
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Remedies and Solutions
Sault Ste. Marie
Remedies and Solutions
Protecting community health in Sault Ste. Marie requires the province to shift from piecemeal, facility-by-facility regulation to a cumulative impact model that accounts for the combined emissions of the entire steelmaking complex and surrounding sources. The individual, per-facility approvals fail to consider the combined effects of each facility’s emissions. This is a major flaw in the province’s pollution control system, exposing Hamilton’s residents to dangerous levels of pollutants known to harm human health. The Ontario government has also repeatedly granted Hamilton’s steel plants extensions and exemptions from the regulations meant to protect local communities. For example, when the new benzene and benzo[a]pyrene standards came into force in 2016, the steel mills were not ready to comply, so the province approved special standards for benzene (exceeding the general limits nearly ninefold), benzo[a]pyrene, and suspended particulate matter. The government then extended those approvals through at least 2023.
Sudbury
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Sudbury
Community Snapshot
Sudbury is northern Ontario’s largest city, with a population of 166,000 people as of 2021. This city is a prominent mining and smelting center, with a continuing legacy of nickel and copper production. By the late 20th century, Sudbury’s vicinity had been severely deforested and tainted by pollution, though major efforts have since restored much of the local greenery. As a mineral-rich area, Sudbury contains several mining operations along with two smelters still active. Local air quality has moderately improved in recent years, but the communities closest to the smelter sites have historically endured the worst air quality.
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Pollution Sources
Sudbury
Pollution Sources
Smelting operations in Sudbury roast and smelt nickel-copper ore, emitting large quantities of sulphur dioxide and dust containing metals like nickel, copper, cobalt, lead, and arsenic. Emissions from furnace stacks and converters also carry toxic metals. This has historically led to contaminated soil in the region. Other local sources include mine operations, which create diesel exhaust and dust from rock crushing/tailing piles. The province has updated air standards for pollutants like nickel in dust–a new annual standard of 0.04 µg/m³ for nickel came into effect in 2023. However, the smelters cannot meet it yet. This led the government to propose a special industry rule exempting Sudbury smelters from the strict limit while they optimize controls–another example of a loophole that endangers locals' respiratory health.
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Cumulative Effects
Sudbury
Cumulative Exposure
With two main smelters and several mining sites, the heavy industrial presence in Sudbury results in cumulative impacts on the region’s air quality. Neighbourhoods nestled around and between the smelters are often breathing air polluted by both facilities. Sulfur dioxide emitted from both facilities also has the potential to create acidic conditions in downwind lakes, posing a risk to communities and ecosystems that rely on the lakes. This problem is intensified when emissions from both facilities are simultaneously released into the air. Moreover, legacy industrial sites (old roast beds, slag piles) still emit dust on dry windy days, adding to cumulative particulates. Sudbury’s mix of ongoing operations and historical pollution that contributes to current exposure results in unhealthy cumulative exposure for the area’s residents.
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Concerns and Impacts
Sudbury
Concerns and Impacts
Historically, the sulfur dioxide emissions in Sudbury have wiped out hundreds of hectares of vegetation in the area and acidified hundreds of lakes. Major liming and tree-planting efforts have since reversed much of this damage; however, the effects of sulfur dioxide exposure on human health can only be mitigated, but not fully undone. This is especially the case with older residents who were exposed to airborne pollutants when emissions were at their peak in years and decades past. In addition to the respiratory health risks posed by sulfur dioxide, the Canadian Centre for Occupational Health and Safety classifies it as a Category 2 germ cell mutagen, meaning that it can lead to genetic damage if chronically inhaled.
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Regulatory Gaps
Sudbury
Regulatory Gaps
As the Ontario government tightened air standards for contaminants like nickel and SO2, they recognized that the smelting and refinery operations will not meet the new standards by the deadline; the MECP thus proposed to exempt the facilities from more stringent standards. This approach creates a loophole where Sudbury’s residents are not protected by the same health-conscious limits that apply in other regions across Ontario. Another gap lies in how legacy contamination is addressed: air regulations cover emissions, but not the historically polluted soils that can still release dust. Cleanup of those falls under other frameworks, which are often slow and resource-intensive.
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Polution Sources
Sudbury
Remedies and Solutions
Sudbury’s continued environmental recovery depends on the province adopting a system that evaluates pollution from multiple smelters and legacy sources together, rather than regulating each emitter in isolation. Companies must be required to demonstrate continuous progress toward the stringent SO2 limits, and if technical or economic barriers exist, the provincial and federal governments could support technology upgrades in a way similar to that seen in Sault Ste. Marie. Augmenting the air monitoring network is also needed: more continuous monitors (for SO₂ and fine particulates) in communities like Copper Cliff, Lively, and Falconbridge, with data available online for residents to see current air quality. Cumulative effects measurements should be formally introduced. For example, an annual review that combines emissions data from both major smelters, plus mines, to evaluate the total pollution load on Sudbury’s population and ecosystem. This could inform if further regulatory actions are necessary. Addressing legacy pollution is also part of the air quality picture; continued soil remediation and dust control at contaminated sites will reduce the resuspension of toxic particles. Sudbury’s re-greening program should persist, as vegetation cover helps trap dust and improve air quality.
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Sault Ste. Marie
Community Snapshot
Sault Ste. Marie has a population of approximately 76,000 people, located on the St. Marys River across from its twin city in Michigan. Traditionally a steel-manufacturing town, it hosts one of Canada’s largest integrated steel mills, along with a history of forestry and shipping industries. As a result, local air quality has been poor for decades. There are also two First Nation communities (Batchewana and Garden River), and rural areas that can be affected by industrial plumes. The legacy of the steel industry looms large in environmental discussions, and residents often note the contrast between the region’s natural beauty and the pollution from steelworks on the waterfront.
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Polution Sources
Aamjiwnaang First Nation + Sarnia
Community Snapshot
Aamjiwnaang First Nation population: ~2500 Sarnia population: ~72000 Both communities are bordered by Sarnia’s “Chemical Valley” – over 60 chemical plants and refineries in the area. The communities’ experience is intertwined with the industry’s benefits and burdens. Residents enjoy employment and infrastructure from industry, yet they spend their entire lives in disproportionate exposure to air pollution. This raises an issue of environmental justice, as Aamjiwnaang First Nation members and low-income Sarnians bear a disproportionate pollution load with their proximity to industrial emitters.
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Pollution Sources
Sudbury
Community Snapshot
Sudbury is northern Ontario’s largest city, with a population of 166,000 people as of 2021. This city is a prominent mining and smelting center, with a continuing legacy of nickel and copper production. By the late 20th century, Sudbury’s vicinity had been severely deforested and tainted by pollution, though major efforts have since restored much of the local greenery. As a mineral-rich area, Sudbury contains several mining operations along with two smelters still active. Local air quality has moderately improved in recent years, but the communities closest to the smelter sites have historically endured the worst air quality.
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Polution Sources
Hamilton
Community Snapshot
Population: 569,000. Located in southern Ontario, Hamilton's economy was built on heavy industry, notably two integrated steel mills and associated metal-processing plants alongside other manufacturing and transportation sectors. In recent decades, Hamilton’s local economy has diversified, but the east end of the city remains an industrial core. Air pollution concerns in Hamilton date back to the mid-20th century, when steel mill emissions and coal-fired power contributed to intense smog. Today, Hamilton enjoys generally better air quality than decades ago, but neighbourhoods near the steel facilities and highway corridors still experience chronically high air pollution levels. This poor air can disperse to lower-altitude parts of the city and remain trapped by the Escarpment, creating health disparities and raising environmental justice concerns that must be addressed.
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Pollution Sources