The increasingly polluted atmosphere is the result of a large amount of pollutants that are released day by day from some source of pollution, which is called emissions. In order to keep emissions within acceptable limits for the environment and human health, the Regulation on limit values of emissions of pollutants into the air from stationary sources (Official Gazette 42/21) was adopted in Croatia, which indicates the maximum permitted release of pollutants into the air from a mobile or stationary source pollution. In order to reduce emissions of pollutants into the environment, measurements must be carried out continuously, as well as the necessary measures if the measured values are not within the prescribed limit values. Continuous measurements of flue gas concentrations released from numerous mobile or stationary sources of pollution, which are also very harmful to the environment and human health, are regulated by the Regulation that gives a realistic picture of the amount of pollutants released from a certain source of pollution and the magnitude of possible air pollution. The paper will define air pollution, what are the types of pollution sources and what are the transmission routes, as well as the consequences it can lead to. Polluting substances will also be described, with an emphasis on floating particles and nitrogen oxides and sulfur dioxide. The purpose of this final paper is to investigate and describe the principle of pollutant emissions measurement and to emphasize the importance of continuous measurement and monitoring of possible changes in air quality.