Particulate matter (PM) is a mixture of solid particles and liquid droplets suspended in the atmosphere and it stands as one of the most important air pollutants. Its fine fraction, PM2.5, which consists of particles less than 2.5 µm in diameter, is of special interest because it can easily enter human respiratory system and therefore can have adverse impact on human health. Many studies have been conducted to monitor PM outdoors, but since people spend most of their time indoors, it is especially important to monitor indoor pollution, both in homes and workplaces. Metal processing techniques such as welding, cutting, grinding, and polishing produce significant levels of PM in metal workshops. PM from these sources, especially from welding, is typically less than 2.5 µm in diameter, often even less than 1 µm in diameter, so it can easily enter human respiratory system. Moreover, it is rich with heavy metal components such as Mn and Zn, which can cause specific health problems such as manganism. It is, therefore, very important to monitor PM levels in metal workshops, but also to monitor health status of the workers exposed to high levels of PM. The aim of this study is to determine whether the exposure to metals of the workers in metal workshops in Croatia is elevated by evaluating the exposure to metals in particulate matter and by biological monitoring. This can possibly lead to new regulations in this area. In order to estimate the levels of exposure to PM, six metal workshops in the vicinity of the city of Rijeka, Croatia, were chosen to participate in the study. Two of them are dealing with the aluminium components and four of them are mainly dealing with the steel and stainless steel components. Three of the workshops (including aluminium workshops) are rather small, with the area of about 200 m2 , and the other three are located in bigger halls, with the area of 400 m2 or more. In the first workshop, two sampling campaigns were performed. In the first one, the PM2.5 samples were collected in a store-room. 12-h samples were taken through 13 days, so that the samples represent daily and weekly changes in PM2.5 levels. In the second campaign, the sampling was performed in the main working room and samples were taken at finer time resolution. During the working time, 1-h samples were taken and one single 12-h sample was taken during the rest of the day. The sampling was performed during three working days. Similar sampling regime was performed in other workshops. During the working time, 1-h or 2-h samples were taken, and during the non-working time 4-h or 8-h samples were taken. The sampling lasted for three working days in each workshop. Additional sampling with an optical particle counter was performed in most of the workshops, during about ten days at each. Additional sapling was performed at two control workplaces: one laboratory and one office at the University of Rijeka. Three consecutive 8-h samples of PM2.5 were taken in each workplace, while the optical particle counter was used over longer period of time. The samples of PM2.5 were collected on thin polytetrafluoroethylene (Teflon) filters with a cyclone sampler. Overall, 234 samples were collected on the filters, including 134 hourly samples, 26 2-h samples, 29 4-h samples, 15 8-h samples and 30 12-h samples. Mass concentrations were obtained gravimetrically and elemental analysis was performed with X-ray fluorescence (XRF) and particle induced X-ray emission (PIXE) techniques. Concentrations of Na, Mg, Al, Si, P, S, Cl, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Pb and Bi were obtained. Additionally, an optical particle counter measured PM concentrations of 6 different fractions from 0.3 to 10 µm in diameter. About 1800 h of data were collected in this way. As a first step to estimate possible health impacts of PM, biological samples were taken from 34 workers who agreed to participate in the study. Samples of hair were analysed from 30 workers from all the workshops included in the study, while 8 samples of nails were analysed from the workers from the first workshop. Additionally, 34 unexposed persons were included in the control group, from which 32 hair samples and 9 nail samples were analysed. Elemental analysis of biological samples was performed with inductively coupled plasma mass spectrometry (ICPMS) and concentrations of Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd and Pb were determined. In most of the workshops, PM2.5 and elemental concentrations showed a pattern clearly connected to the working activities. The highest concentrations of almost all elements were obtained for the first workshop, during the second sampling campaign. Hourly PM2.5 concentrations in this period were up to 2900 µg/m3 , while Mn and Fe hourly concentrations were up to 45 and 1400 µg/m3 , respectively. In this and other steel workshops, Fe was a predominant element, making up to 50 % of total mass. Mn was one of the most recognizable elements, being one of the main components of welding electrodes. In the aluminium workshops, the total concentrations were much lower and with much different elemental compositions. In the second workshop, the maximum hourly PM2.5 concentration was 300 µg/m3 , while in the third workshop the maximum PM2.5 concentration was only 38 µg/m3 . As expected, Fe was not the predominant element, but neither was Al, because aluminium parts were neither welded nor heated in any other way that could produce fine particles. Much lower PM2.5 concentrations were measured in control workplaces, where the maximum PM2.5 concentration was only 9 µg/m3 . Concentrations and composition of PM2.5 in control workplaces were comparable to the data obtained previously in the outdoor air in the Rijeka city centre. In the hair samples, significantly higher concentrations of Al, Ti, Mn, Fe and Pb were measured in samples of workers in steel workshops than in the control samples. The highest concentrations of these metals were found for samples of workers from the first, fourth and fifth workshop, were the highest PM2.5 concentrations were measured as well. Although a very small number of nail samples was analysed, higher concentrations of Ti, Mn and Fe in the samples of workers are clearly visible. This indicates that these metals were deposited in analyzed tissues after being inhaled as particulate matter. It should be further investigated if these metals are deposited in other tissues and organs, such as liver or brain and whether that causes health problems. The results of this investigation show that deposition of metals in tissues of workers occurs even under PM concentrations that are far below limit values. For possible revision of current limit values it is necessary to carry on with further research wchich would investigate health status of the workers.