“…shutdowns are a major cause of “abnormal” emission events, according to a 2012 report from the Environmental Integrity Project. Short-term impacts of these events can be “substantial,” because “upsets or sudden shutdowns can release large plumes of sulfur dioxide or toxic chemicals in just a few hours, exposing downwind communities to peak levels of pollution that are much more likely to trigger asthma attacks and other respiratory systems.”
motherjones.com