Getaround launches peer-to-peer car sharing service and study in Portland; ZipCar invests in peer-to-peer service Wheelz
Volvo Car Corporation, Ericsson and partners in plug-in vehicle smart on-board charging research project

Satellite study finds NO2 and SO2 pollution over Canadian oil sands region comparable to that of a large power plant

North American, annual-mean OMI (Ozone Monitoring Instrument) tropospheric NO2 VCDs (vertical column density) (2005–2010) averaged onto a 0.25° x 0.25° grid. The oil sands region within Alberta is indicated. McLinden et al. Click to enlarge.

Atmospheric nitrogen dioxide and sulfur dioxide pollution over Canada’s oil sands region is comparable to that seen over a large power plant, according to satellite remote sensing observations of the two pollutants reported in a paper in Geophysical Research Letters, a publication of the American Geophysical Union.

The international team of researchers created high-resolution maps that revealed distinct enhancements in both pollutant species over an area (roughly 30 km x 50 km, or 19 miles x 31 miles) of intensive oil sands surface mining at scales of a few kilometers. The magnitude of these enhancements, quantified in terms of total mass, are comparable to the largest seen in Canada from individual sources, the team said.

For both gasses, the levels are comparable to what satellites see over a large power plant—or for nitrogen dioxide, comparable to what they see over some medium-sized cities. It stands out above what’s around it, out in the wilderness, but one thing we wanted to try to do was put it in context.

—Chris McLinden, a research scientist with Environment Canada

The scientists found that sulfur dioxide amounts peaked over two of the largest mining operations in the Alberta oil sands, with a peak of 1.2x1016 molecules per square centimeter. Nitrogen dioxide concentrations reached about 2.5x1015 molecules per square centimeter. When researchers looked at the concentrations over the years using older satellite information, they found that the amount of nitrogen dioxide increased at 10.4 ± 3.5% each year between 2005 and 2010, keeping pace with the growth of the oil sands industry. An increase in SO2 was also found, but given larger uncertainties, was not deemed statistically significant.

It is important to provide some context for these results. The OMI SO2 enhancement over the oil sands is as large as that from any other individual emissions source in Canada, including the large base-metal smelting operations in Manitoba and Ontario. These results may also be compared with OMI SO2 enhancements seen near US coal-burning power plants...Values over the oil sands are similar as those of moderate to large power plants with annual emission rates of 100 kt[SO2]. The situation with NO2 is somewhat different: while the OMI NO2 signal is significant and comparable to that measured over large, individual sources such as coal-burning power plants, it is smaller than what is observed over large metropolitan areas....The city of Edmonton, with a population of approximately one million and large power plants and oil refineries nearby, has NO2 VCDs that are a factor of 2–3 larger and cover a much larger area.

—McLinden et al.

The independent report on the levels of these airborne pollutants, which can lead to acid rain if they are in high enough concentrations, is a part of Environment Canada’s efforts to monitor the environmental impact of the oil sands’ surface mines. While some land-based measurements have been taken at particular points by other researchers, and a NASA airplane made another set of localized measurements, no one had calculated the overall extent of the oil sands’ air quality impacts including the giant dump trucks, huge refining facilities where the bitumen is processed, and more.

To do that, McLinden and his colleagues turned to satellite data. Several satellites orbiting Earth detect sunlight that passes through the atmosphere and is reflected back up to the space. Based on the patterns of reflected wavelengths, scientists can calculate the concentration of certain gasses—in particular nitrogen dioxide and sulfur dioxide. It’s a relatively new way to study pollution over small areas, McLinden said.

It’s important to examine the overall impact of the excavation and processing from the oil sands, said Isobel Simpson, an atmospheric chemist with the University of California at Irvine. She was not involved in this study, but previously participated in the airplane-based research of air quality over the oil sands.

Simpson called for broader, future studies that would measure additional pollutants and map their extents. With the oil sands industry expanding, she said, the area needs more monitoring.


  • McLinden, C. A., V. Fioletov, K. F. Boersma, N. Krotkov, C. E. Sioris, J. P. Veefkind, and K. Yang (2012), Air quality over the Canadian oil sands: A first assessment using satellite observations, Geophys. Res. Lett., 39, L04804, doi: 10.1029/2011GL050273



Is it equivalent to one or one hundred+ coal fired power plants?


These folks should be more concerned about gases from active volcanoes which exceed those from all human activity combined.


@ Mannstein

The volcanologists say not.

Gas studies at volcanoes worldwide have helped volcanologists tally up a global volcanic CO2 budget in the same way that nations around the globe have cooperated to determine how much CO2 is released by human activity through the burning of fossil fuels. Our studies show that globally, volcanoes on land and under the sea release a total of about 200 million tonnes of CO2 annually.

This seems like a huge amount of CO2, but a visit to the U.S. Department of Energy's Carbon Dioxide Information Analysis Center (CDIAC) website ( helps anyone armed with a handheld calculator and a high school chemistry text put the volcanic CO2 tally into perspective. Because while 200 million tonnes of CO2 is large, the global fossil fuel CO2 emissions for 2003 tipped the scales at 26.8 billion tonnes. Thus, not only does volcanic CO2 not dwarf that of human activity, it actually comprises less than 1 percent of that value.

On average, human activities put out in just three to five days, the equivalent amount of carbon dioxide that volcanoes produce globally each year. This is one of the messages detailed in a new article "Volcanic Versus Anthropogenic Carbon Dioxide" by Terrance Gerlach of the U.S. Geological Survey appearing in this week's issue of Eos, from the American Geophysical Union.


Correction: "last year's issue of Eos, from the American Geophysical Union"

BTW, if you're going to challenge this, don't bother arguing with me - argue with the experts.


Thank you ai_vin for the pertinent data and to set the records straight.

Canada's underestimated latest man made CO2 emissions are almost 800 million tonnes/year. The real emissions could be well over 1000 million tonnes/year because the fossil fuel industries probably report less than 50% of their emissions.


Some days I wonder if the posters like mannstein are people whose "education" comes from right-wing websites and talk radio, or if they are actually paid trolls.

I think I'd have a little more faith in humanity if he was being paid. Cynicism isn't as bad as fanatical stupidity.


Yeah E-P, for a lot of people its political, but for a good scientist it is the facts that matter.

Stan Peterson

What is that colored graph. A picture of the US in 1960 measuring humidity in gorgous red?


An article that is largely taken from "Air Pollution" by Jeremy Colls would be a useful (and on topic) read: Air Pollutants

According to Colls, all natural sources combined contribute about 26% of the SO2 emissions into the atmosphere.


Typo: Should have been 24%. That includes volcanoes.

The comments to this entry are closed.