This paper develops a model of an optimal regulatory program for greenhouse gases (GHGs) emissions that accommodates the benefits due to reductions of co-pollutants including: sulfur dioxide (SO2), nitrogen oxides (NOx), volatile organic compounds (VOC), and fine particulate matter (PM2.5)....

The sulfur dioxide (SO₂) cap and trade program established in the 1990 Clean Air Act Amendments is celebrated for reducing abatement costs ($0.7 to $2.1 billion per year) by allowing emissions allowances to be traded. Unfortunately, places with high marginal costs also tend to have high marginal...