The Baie-Comeau Smelter has a prebake anode plant and a Söderberg plant which ceased operations during 2013. Söderberg anodes, a mixture of tar pitch and coke, bake during the electrolysis process rather than in a dedicated oven like at the other plants. This results in polycyclic aromatic hydrocarbons (PAH) emissions. In the Söderberg potrooms, approximately 85% of emissions are captured at the source to be treated by dry scrubbers. The remainder is emitted through the roof vents.
Total emissions decreased in 2011 and 2012 following improvements in the quality of the raw materials and pot operation. Emissions increased only slightly in 2013, during the last months of operation of the Söderberg pots, since extra care was given to operations during the dismantling to control PAH emissions.