A major pollutant from the coal and steel industries is SO2. This pollutant has been determined to be one of the causes of acid rain.
Industry already has an alternative to letting the gas out into the atmosphere.
These are called scrubbers and they remove the gas from smokestacks before it enters the atmosphere. The problem is that scrubbers are expensive and used to be inefficient, so that the industry had to monitor how much smoke it was putting out and could not exceed some specific level. A literature search should yield some specific designs, the chemical reactions used and the cost of using the scrubbers. Argonne National Laboratory, Division of Educational Programs, Harold Myron, Ph.D., Division Director.