Reprinted in this pamphlet is the fifth annual directory of air pollution control products as compiled in the "Journal of the Air Pollution Control Association" for December, 1971. The 16-page guide lists manufacturers of emission control equipment and air pollution instrumentation under product classifications as derived from McGraw-Hill's "Air Pollution Handbook", chapters 10, 11, and 13. Product classes for emission control equipment are inertial separators, scrubbers and washers, fabric and fiber collectors, and other control techniques and apparatus, together with numerous sub-classes within each category. Air pollution instrumentation topics and sub-topics include samplers and collectors, analytical equipment, and miscellaneous instrumentation. The final portion of the guide contains an alphabetical listing of manufacturers and their addresses. (BL)