How do countries work together to solve the global pollution problems?

Coal contains up to 4% sulfur. Other materials contain sulfur. The chief cause of acid rain has been the burning of coal and the smelting of materials. First. Countries have made it illegal for individuals to burn coal in their fireplaces. This has made it so that individual houses are not putting sulfuric acid into the air. Second, countries have forced power plants and smelters to put scrubbers inside of chimneys of coal burning electric plants. The scrubbers have reduced the amount of sulfuric acid entering the air. Still, Since Congress has not forced all plants to retrofit scrubbers, a tremendous amount of sulphuric acid still goes into the atmosphere and returns as acid rain.