The main idea was to examine and classify dust particles which emerge during manual metal arc welding. The testing measurements were done with Zambelli EGO TT air testing quality device. The measured air temperature was 26 °C and time interval at which welding procedures were done was one minute. Construction steel was used as basic material and cellulose electrode was used as additional material. The quantity of absorbed air through filter was 3 litres. Two test were conducted, the first with the usage of ventilation device, and the second without the usage of ventilation device. Particle analysis was done on electronic microscope with purpose of finding out the quantity, size and geometry of dust particles. The classification of dust particles was done according to the standard of ISO 13322 »Particle size analysis«.