For years, Indigenous communities living near Canada’s oil sands have worried about the health impacts of the cloud of air pollution rising from the vast industrial mining complex. A recent study shows the problem is far worse than previously thought, with air pollution levels from oil sands operations up to 64 times higher than that reported by industry.

Canada’s oil sands are the fourth-largest oil deposit on Earth and among the most energy-intensive to access and process. Buried beneath the boreal forest of northern Alberta, bitumen is a thick, heavy tar-like form of petroleum that coats subsurface sand. It is extracted using both open-pit and in-situ mining, which involves pumping steam underground. Current production is 3.3 million barrels per day.

Typically, companies operating in the oil sands calculate air pollution levels using a “bottom-up” approach as required by law — estimating emissions generated at each step of the petrochemical extraction process, including, for example, contaminants rising from smokestacks, heavy machinery and other sources, then adding those figures together to come up with the total emissions.

But the 2024 study finds that those methods, while they may be legal, are woefully inaccurate. Using specialized aircraft-based sensors, researchers from Environment and Climate Change Canada (the federal department responsible for coordinating environmental policies and programs), and Yale University took real time measurements and determined that oil sand operations are emitting between 20 and 64 times more air pollution than previously reported.

“Measured facility-wide emissions [from the oil sands] represented approximately 1% of extracted petroleum, resulting in total organic carbon emissions equivalent to that from all other sources across Canada combined,” the study authors write.

The findings, published in Science in January 2024, underscore how current methods of measuring oil sands air pollutants are grossly underestimating emissions. These results raise questions not addressed by the study of whether these underestimates could end up underrating impacts on human health and the environment.

“The magnitude of emissions observed from oil sands operations was surprising, compared both to their reported emissions and to the total from all anthropogenic sources across Canada,” study authors John Luggio and Drew Gentner tell Mongabay in an email.

It’s too early to know how this joint government-academic study might influence future pollution monitoring and emission reductions.

Real time aerial measurements vs. industry estimates

To capture the release of air pollutants in real time, the researchers flew above 17 oil sands operations in 2018 and measured the total reactive organic chemicals upwind and downwind of the facilities. This included volatile organic compounds (VOCs), as well as intermediate volatility and semi-volatile organic compounds (I/SOVs), which are usually overlooked in the industry’s bottom-up measuring approach. Yet all these compounds are of concern because they directly contribute to local air pollution and they can react with other airborne compounds to form particulate matter (including PM2.5 fine particles) that persist and can be carried farther downwind. All these pollutant types can cause health problems.

While the 2024 study didn’t directly address human health impacts, the pollutants emitted by oil sands operations are hydrocarbons — a class of compounds known to be harmful to health and includes known carcinogens, endocrine disruptors and compounds affecting cognition. Among these pollutants are benzene, nitrous oxides and others, which can impact respiratory, cardiovascular and nervous systems and more.

Hydrocarbons exist as gases but some, such as VOCs, react with existing compounds in the atmosphere, leading to secondary air pollutants and contributing to the formation of particulate matter, including PM2.5s — tiny particles that penetrate deep into the lungs or enter blood. PM2.5s are also a component of dust like that produced by oil sands mining, as well as the wildfire smoke like that seen over Canada in the summer of 2023. These fine particulates can cause local air pollution but also travel far downwind and can have major harmful health effects, including respiratory and cardiovascular impacts, lung cancer, premature birth and more.

Overall, the researchers found that the total amount of air pollution from the oil sands is similar to that found over large American cities like Los Angeles, and as noted, equivalent to all other human-caused sources of air pollution in Canada combined.

Some of the detected oil sands air pollution was coming from vast open-pit mines, which was expected. But the researchers also found it arising from in-situ underground mining, which currently makes up about half of oil sands production but is expected to expand in the future.

The findings also raise questions about how the industry should manage mine waste called tailings. A large spill of toxic wastewater from a tailings pond at Imperial Oil’s Kearl site in the oil sands in 2023 alarmed First Nations communities and highlighted the need to reduce the volume of liquid tailings storage — ponds that continue growing as oil sands are mined. One such storage method requires the drying of tailings, but the 2024 study found that drying leads to higher off-gassing, turning a water pollution problem into an air pollution problem.

While this study looked specifically at Canada’s oil sands, Luggio and Gentner note that it also suggests potential blind spots in calculating emissions from other industrial activities — including various types of unconventional oil and gas production.

Jeffrey Brook, associate professor at the University of Toronto’s Dalla Lana School of Public Health, who was not involved in the study, says this research represents the latest of many studies that show industry-reported figures consistently underestimate emissions from the oil sands. “It continues to be the more you look, the more you find,” he says.

Previous studies, for example, have found that greenhouse gas emissions from oil sands surface mining operations were 64% higher than industry-reported figures; that the oil sands are one of the largest human-caused sources of secondary organic aerosols in North America; that air pollutants from the oil sands that rain down from above are creating toxic concentrations of polycyclic aromatic compounds (PACs) in the Athabasca River; and more.

Some types of PACs are known carcinogens and may damage the immune and reproductive systems. A 2010 PNAS study found that the oil sands industry was releasing numerous pollutants into the watershed through air and water pathways, 13 of which are elements listed as priority pollutants under the U.S. Environmental Protection Agency’s Clean Water Act.

Indigenous community public health at risk?

Brook also works as an air pollution consultant for the Fort McKay First Nation, a community composed of about 700 people, which sits in the heart of the oil sands, with some mines just a few kilometers away. Residents in Fort McKay can often smell a burnt rubber-like odor in the air, Brook says, and lately people have become especially worried about the dust. It settles on cars, coats playgrounds, finds its way into homes — and into people’s lungs.

Science doesn’t currently know enough about the health implications of low-dose long-term exposures to multiple pollutants that people in communities like Fort McKay are experiencing, Brook says. Health studies tend to focus on single pollutants, he explains, but don’t consider that people are being chronically exposed to a range of toxins found in air and water and possibly in harvested traditional foods such as fish and game.

Aliénor Rougeot, the climate and energy program manager with Environmental Defence, an NGO, says that industry and government haven’t paid enough attention to First Nation communities’ long-standing worries about air quality and health. “Their concerns have always been brushed aside by saying, ‘No, no, look at industry’s reported emissions. This is all fine.’ And so, to discover that we’re talking about like 20 to 64 times more, I think was deeply angering,” Rougeot says.

Industry representatives did not respond to a request from Mongabay for comments on the study.

Luggio and Gentner noted by email that “the Government of Canada is working with partners, including industry, to better measure emissions from the oil sands … [and] will take ongoing scientific work, such as this study, into consideration as it moves forward.”

The inaccuracy of current emissions reporting has very concrete policy implications. Decision-makers use computer modeling to judge the potential impacts of new projects, but Brook notes there’s a common mantra concerning the data used in modeling: “Garbage in, garbage out.” Industry maintains it is reporting what’s required by government, Brook says, but it isn’t proactively making sure it has accurate numbers.

“We hear over and over again, from the Alberta government and from industry, that we have some of the best environmental reporting in the world,” says Joe Vipond, a physician and past president of the Canadian Association of Physicians for the Environment, who was not involved in the study. But “it just doesn’t seem to be borne out by deeper analysis.”

Banner image: Oil refinery smokestacks along the Athabasca River, in northern Alberta, Canada. New measurements reveal that the amount of air pollution emitted from oil sands operations is far higher than reported by industry and equal to all other human-caused air pollution sources in Canada combined. Image by iStock.com/Dan Prat.

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Citations:

He, M., Ditto, J. C., Gardner, L., Machesky, J., Hass-Mitchell, T. N., Chen, C., … Gentner, D. R. (2024). Total organic carbon measurements reveal major gaps in petrochemical emissions reporting. Science, 383(6681), 426-432. doi:10.1126/science.adj6233

Liggio, J., Li, S. M., Staebler, R. M., Hayden, K., Darlington, A., Mittermeier, R. L., … & Vogel, F. (2019). Measured Canadian oil sands CO2 emissions are higher than estimates made using internationally recommended methods. Nature communications. doi:10.1038/s41467-019-09714-9

Liggio, J., Li, S. M., Hayden, K., Taha, Y. M., Stroud, C., Darlington, A., … & Gentner, D. R. (2016). Oil sands operations as a large source of secondary organic aerosols. Nature, 534(7605), 91-94. doi:10.1038/nature17646

Kelly, E. N., Short, J. W., Schindler, D. W., Hodson, P. V., Ma, M., Kwan, A. K., & Fortin, B. L. (2009). Oil sands development contributes polycyclic aromatic compounds to the Athabasca River and its tributaries. Proceedings of the National Academy of Sciences, 106(52), 22346-22351. doi:10.1073/pnas.0912050106

Kelly, E. N., Schindler, D. W., Hodson, P. V., Short, J. W., Radmanovich, R., & Nielsen, C. C. (2010). Oil sands development contributes elements toxic at low concentrations to the Athabasca River and its tributaries. Proceedings of the National Academy of Sciences, 107(37), 16178-16183. doi:10.1073pnas/1008754107

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Air PollutionConflictDeforestationEnvironmentenvironmental justiceEnvironmental LawEnvironmental PoliticsFossil FuelsGovernanceIndigenous PeoplesIndigenous RightsIndustryLand ConflictMiningOilOil SandsPollutionWater PollutionAlbertaCanadaNorth America

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