New evidence of unequal contribution to health burden reshaping air pollution control in waste-to-energy plants.

Waste-to-energy (WTE) incineration has been long argued for the emission of hazardous flue gas pollutants (FGPs), while the contribution to health burden of individual components is ambiguous, resulting empirical control measures. We constructed a comprehensive framework to assess the health burden by monetizing premature mortalities, combining nine kinds of regulated FGPs from WTE plants. NOx and SO2 were identified as the main contributors to health risk, accounting for around 88.87 % and 6.97 % respectively in 2020. The annual social cost of mortalities (SCM) increased from USD 6.09 billion in 2010 to USD 13.60 billion in 2015, and to USD 16.71 billion in 2020, related to the surge in WTE capacity, which grew 10-fold over the past decade. The SCM per ton of municipal solid waste, however, significantly decreased from 329 USD/t in 2010 to 213 USD/t in 2015, and to 88 USD/t in 2020, due to updating of the standards and technological advances, pushing the emission factors down by 33.75-98.63 %. SCM will be continuously mitigated by the tightened emission limits, with the greatest benefits seen in a reduction of up to 50 % in NOx to 80 mg/m3 by selective catalytic reduction and selective non-catalytic reduction. Coastal regions were recommended as a high priority for further control, on account of their greater population density, higher economic level, and greater WTE capacity, which made up 60-71 % of total reduction benefits. These findings provide data support and recommendations for policymakers and stakeholders to mitigate FGPs emissions to efficiently reduce the health risk of WTE plants.