Manganese is widely distributerd in constantly changing complex natural relations involving physical, chemical, and biologic activity. It is used primarily in the production of iron and steel, and its emission to the atmosphere is principally the result of this use, either directly or indirectly. Much of the published emission data is old and must be used with caution and with due consideration given to various qualifying factors, including location, atmospheric conditions, degree of control, and method of sampling and analysis. Manganese pollution of the atmosphere is currently a local problem, for the most part an in-plant rather than an ambient-air problem. For the 12-year period ending in 1965, average U.S. urban ambient- air concentration was approximately 0.10 Ug/m3. Maximum concentrations exceeded 10 ug/m3 but appear to have been of that order of magnitude. Manganese pollution of water does not appear to be a serious matter, except under very unusual local conditions. There are few reports of manganese contamination of soils.