Delaware has joined another multi-state lawsuit against a US Environmental Protection Agency (EPA) regulation.   The Obama era EPA wrote the Cross-State Air Pollution Rule to limit power plants in upwind states, such as Pennsylvania, from polluting downwind states, such as Delaware.  The DC Appeals Court overturned the regulation as it required states to reduce emissions by more than their relative contributions to downwind pollution, and didn’t allow the states to devise their own compliance plans as required by the Clean Air Act.  In 2016 the EPA released an updated regulation that set more appropriate goals and allowed states to establish their own plans to meet the goals.  
 
            The primary issue is the emission of nitrogen oxides (NOX) that contribute to formation of ground level ozone. By the end of 2017 every power plant in the areas covered by the new rule met the rule.  Pennsylvania power plants reduced NOX emissions 60 percent between 2016 and 2017 alone, and another 7 percent in 2018.  In Delaware, only New Castle County fails to meet the National Ambient Air Quality Standard for ozone of 70 parts per billion average in an eight hour period.  However, maximum ambient levels fell from 78 PPB in 2016 to 72 in 2018.  Delaware easily meets air quality standards for other pollutants.  
 
Power plants now account for only a few percent of NOX emissions.  About two thirds of NOX emissions come from motor vehicles.  Required emission improvements in motor vehicles are reducing emissions about 6 percent a year as older vehicles leave the fleet.  Consequently, the EPA models project New Castle County will meet the ozone standard by about 2022, and it may be sooner.  Western forest fires contributed significantly to the above standard ambient levels in 2018.
 
So, why are states like Delaware suing the EPA?  These states are not satisfied just having clean air.  They want to force other states to shut down their coal-fired power plants by any means available.  The preferred solution would force the adoption of expensive carbon dioxide taxes or cap and trade programs that have left the suing states with uncompetitive electricity rates.  An earlier lawsuit has a similar goal.  A comparison of states shows states with such programs have lost a third of their energy intensive businesses (Delaware lost half) lowering incomes, and economic growth. Ironically, the shut-down of power plants in the suing states forced them to import more electricity from the very states they are trying to force out of the electric generating business! Apparently, misery loves company.