Air is a mixture of gases without which life on Earth would not be possible. The process of industrialization and population growth has rapidly increased the pollutant concentration in the air, which is harmful for human health and the environment. Air pollution is spread over long distances, so this problem requires a high level of international cooperation. In the Republic of Croatia, air quality control is regulated by the Air Protection Act (NN 130/11, 47/14) and the Environmental Protection Act (NN 80/13, 78/15), which define the measures for the protection and improvement of air quality. Institutions involved in air quality monitoring activities are: the Ministry of Environment and Nature Protection, the Croatian Agency for the Environment and Nature, the Croatian Environment Agency and the State Institute for Nature Protection. With the aim of informing the public, the Croatian National Environmental Pollution Register operates. It is an online portal that uses the Environmental Pollution Register as a source of data that compiles data based on the Environmental Pollution Registry Policy. Air quality research activities include monitoring of changes in the amount of harmful substances in the air that might have negative impact on people, the climate and the environment. The Meteorological and hydrological institute of Croatia allocates measuring stations and monitors the air quality using metering devices. „Osijek – 1“ is a national measuring station which is active from January 12th 2004. However, there are ten more measuring stations in Osijek and they are part of local measuring network. Kopački rit is nearest rural measuring station. In the city Osijek the highest measured concentrations were for fine particles - PM10. Therefore, the concentration of such particles have been monitored through a long period of time.