The purpose of the master thesis was to examine whether in the context of formal air impact assessment, the assessors use expert evaluation methods, or simply compliance assessment without transparent analytical work. We conducted a detailed review of 28 environmental impact reports, which have been prepared in the procedures of environmental impact assessment (EIA). We used the description method and a comparision to determine approaches, methods and the overall quality of the evaluations. Statistical methods have been applied to determine the reliability of the forecasts. The findings of the review clearly show that the environmental impact assessment focusing on the compliance assessment as the core of the evaluation system is not adequate and does not contribute to the optimization of projects, the selection of the best alternative, and to the achievment of general environmental protection and sustainability goals. The comparison of predicted emission values and the measured values performed after project implementation showed that in majority of the cases the difference is above 30% (this figure has been adopted based on general ''safety factor'' of 25% applied in the process, construction and civil design). This suggests that predictions in formal EIAs are not a good and trustworthy indicator of air quality (both emissions and imissions). We pointed out incosistencies in the implementation of the formal air impact assessment and made suggestions for improvements.