Welding is the principal industrial process used for joining metals, but at the same time, it's the significant source of toxic fumes and gases emission. With the advent of new types of welding procedures and consumables, the number of welders exposed to welding fumes is growing constantly in spite of the mechanisation and automation of the process. Having in mind that, in some cases, toxic fumes and gases can be over the respective limits for toxic substances, one of the most important requirements for chosen welding procedure is its harmlessness to the environment. The health aspects associated with welding are complex and the industry is continuing its research to evaluate the effects of the welder's exposure to typical constituents of welding fumes and gases, as well as its impact on what concerns climatic changes. The aim of this paper is to estimate the influence of the type of filler material on the emission of toxic substances, and to show the potential hazards. In order to determine that effect, microalloyed steel has been welded using two different filler materials (metal cored wire and self-shielded wire). The concentrations of emitted total dust, CO2, CO, SO, Mn, Ni, Al, Cr, Cr(VI), Ca and P were measured. By comparing results for both filler materials, it was established that the special attention must be paid to the high concentration of manganese and CO in metal cored wire, as well as high concentrations of phosphorus and aluminum in self-shielded wire. Also, conducted experimental measurements of emission of certain elements did not show higher toxicity of self-shielded wire compare to metal cored wire, what is in the contrast with previous studies. [ABSTRACT FROM AUTHOR]