Which substance has historically been targeted by cap-and-trade programs to reduce acid deposition?

Which substance has historically been targeted by cap-and-trade programs to reduce acid deposition?

• A. Ozone.
• B. Sulfur dioxide.
• C. Carbon dioxide.
• D. Particulate matter.

Answer: (B)

Cap-and-trade programs aimed to cut the pollutants that cause acid rain. Sulfur dioxide, released mainly from burning coal, reacts in the atmosphere to form sulfuric acid and sulfate particles that return to Earth as acid rain, harming lakes, soils, forests, and buildings. The trading system set a firm limit on total SO2 emissions and allowed reductions to occur where cheapest, encouraging power plants to adopt cleaner technologies or switch fuels. This made sulfur dioxide the primary target because it is the dominant precursor to acid deposition and because it’s straightforward to monitor and regulate. The other substances listed do not drive acid rain in the same way: ozone is a smog-related pollutant, carbon dioxide is tied to climate change, and particulate matter is a broad category with various sources and effects, not the main focus of the cap-and-trade effort for reducing acid deposition.

Cap-and-trade programs aimed to cut the pollutants that cause acid rain. Sulfur dioxide, released mainly from burning coal, reacts in the atmosphere to form sulfuric acid and sulfate particles that return to Earth as acid rain, harming lakes, soils, forests, and buildings. The trading system set a firm limit on total SO2 emissions and allowed reductions to occur where cheapest, encouraging power plants to adopt cleaner technologies or switch fuels. This made sulfur dioxide the primary target because it is the dominant precursor to acid deposition and because it’s straightforward to monitor and regulate. The other substances listed do not drive acid rain in the same way: ozone is a smog-related pollutant, carbon dioxide is tied to climate change, and particulate matter is a broad category with various sources and effects, not the main focus of the cap-and-trade effort for reducing acid deposition.