In the present study, the author examined the physicochemical properties and the atomospheric levels of manganese and other heavy metals in the suspended particulate matter of a welding workshop and a residential area neighboring an iron works. α-Fe(2)O(3) and Fe(3)O(4) were the main components of the suspended particulate matter collected in the atomosphere around both areas. The total suspended particulate matter of the welding process (welding TSP) also contained MnFe(2)O(4) formed from Fe(3)O(4) by exchange of Fe with Mn, metalic Mn and an alloy from of Mn-Fe. These findings were obtained by X-ray diffractometry. Observation through the electron microscope showed the presence of fin particles (0.5-1.5μm) in welding TSP, and attention should be given hazards. The concentration of the metals in the welding TSP was about 10 to 30 times higher than that in the covering materials of the welding rods. Exposure levels of manganese in the welding workshop at a breathing zone ranged from 0.4 to 1.0μg/m(3) and the levels were reduced to one tenth by using a welding mask. Levels of manganese have decreased from a maximum median levels of 0.24μg/m(3) in 1971 to 0.15μg/m(3) in 1981. The order of content of the metals in the paticulate matter was: Fe, Cu, Zn, Pb, Mn, V, Ni, and Cd.