They did exactly that with SO2: In the US, the 1990 Clean Air Act Amendments established an emissions trading system to reduce emissions of SO2 from fossil-fue

They did exactly that with SO2: In the US, the 1990 Clean Air Act Amendments established an emissions trading system to reduce emissions of SO2 from fossil-fuel burning power plants located in the continental 48 states of the United States. (...) Caps on emissions were implemented by issuing tradable allowances that in total equalled the annual cap level. To comply, sources were required to surrender one allowance for each ton of emissions. (...) https://www2.dmu.dk/atmosphericenvironment/expost/database/docs/us_emissioncaps.pdf https://www2.dmu.dk/atmosphericenvironment/expost/database/d...