Fine aerosol pollution is one of the most important factors in air pollution monitoring. Industrial production often represents significant source of aerosol pollution in surrounding areas, and therefore, it is important to understand its impact on air quality. In order to investigate contribution coming from the oil refinery to air pollution, PM2.5 (particulate matter with aerodynamic diameter smaller than 2.5 μm) samples were collected in the vicinity of an oil refinery during the 1‐year period. At the same time, PM2.5 was sampled in the city of Rijeka, Croatia, at the distance that is about 10 km far from the refinery. This site was used for comparison. The sampling was performed with two cyclone samplers on thin polytetrafluoroethylene filters. PM2.5 was sampled for 24 h every other day, simultaneously at both locations. In total, 306 samples were collected. The samples were analysed using X‐ray fluorescence and particle‐ induced X‐ray emission to obtain concentrations of 17 elements from Na to Pb. Additionally, concentrations of black carbon were determined using laser‐integrated plate method. It was found that concentrations of S, V, and Ni, elements characteristic for oil burning, were substantially higher at the refinery sampling site comparing to the reference location. Obtained concentrations were statistically evaluated by performing positive matrix factorization to identify oil refinery as one of the pollution sources in the vicinity of such a facility. The same method was also performed at the urban site where the contribution from oil refinery was not separated from other similar sources.