The refining of bitumen is a two-stage process. Number one, you have to upgrade the resource, so you have to take some of the carbon out of it and you have to add hydrogen to it. That's known as upgrading, and there are several upgraders in the Fort McMurray region, and, yes, they are primary sources of acidic emissions.
Once you've refined the bitumen you have a product called synthetic crude. That product then needs to go through a complex refinery where you have to deal with the acids, the sulphur, and heavy metals in the synthetic crude.
So it's a two-stage process. Light oil is only a one-stage process. So, yes, we are looking at two to three times more air pollution than you would if you were refining light oil.