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Average annual levels of sulphur dioxide are estimated at about 20 times what they would naturally be over a large area from Fort MacMurray to about 100 kilometres north. Nitrogen dioxide is estimated to be at least 10 times pre-development levels — although the report acknowledges hard data from that time is spotty.

And if all the projects that have been announced publicly or are in the regulatory process go ahead, the pollutants are projected to exceed what are supposed to be absolute caps.

Sulphur dioxide will reach average annual concentrations of 21.1 micrograms per cubic metre of air, just over the plan’s limit of 20 micrograms. Nitrogen dioxide will reach 59.5 micrograms, well over the limit of 45.

Randall Barrett, director of Alberta Environment’s northern region, said the projections are derived from models deliberately designed to overestimate emissions as a way to ensure caution.

“It shows us we have to be very diligent in how we are setting pollution controls for any plants in this area, because the computer models are predicting that we are getting close or over some of the air quality (levels).”

Regulators use the models to determine what sort of emission controls to impose on applicants, said Barrett.

“What would likely happen is they would go to the most stringent type of air quality pollution control, because the models are predicting you could be over the limit.”

Barrett said actual air monitoring data continues to show both sulphur and nitrogen dioxides remain well under their caps. If those gases increase as more facilities come on stream, the plan includes “trigger” levels that would require industry to improve its pollution controls.