Atmospheric pollutants have a negative effect on the plants; they can have direct toxic effects, or indirectly by changing soil pH followed by solubilization of toxic salts of metals. Large number of studies have investigated the possible effects of ambient air pollution on  vegetation and air pollution in stomata number and size and stomatal apparatus. The primary aim of this study was to impact air pollution from the aspect of presence SO2, NOX, CO2, O3 and PM10 on vegetation in the city of Banja Luka and stomatal response to air pollution, through a review of existing research.

Urban forests are part of the public city space and have multiple significance. Various roles of greenery (health, social, aesthetic, cultural, educational, etc.) improve the quality of life in the city. Urban forests can play key roles in mitigate stormwater runoff, improve air quality, reduces noise level, store carbon, etc. The system of green areas in a continuous and dynamic interaction with the built structure in a city. Because of the above, subject of the research is determining the state of greenery in the Banja Luka area and the changes that accompany it and to suggest the planning of green areas and protect them.