Internal fire carries a real threat to health and life, not only of the injured people inside but also rescuers. This is due to the impact of toxic gases, as well as the possibility of dynamic and at the same time dangerous fire phenomena. Despite the constant progress of knowledge about internal fires and the phenomena governing them, as well as the development of technologies and tactics to fighting them, it is still difficult to locate a fire. Researches carried out over the last years, aimed at improving the effectiveness and quality of firefighting activities in residential areas, have now created the most effective and safe technique known as positive pressure attack. It is based on carrying out extinguishing activities inside a fire-covered room under the cover of air generated by mechanical-positive pressure ventilation. Appropriate execution of this technique is possible only through systematic practical exercises supported by thorough theoretical knowledge in the field of fire development dynamics. Taking into account the latest achievements of specialized research centers in the world, this paper presents and characterizes the most important components of the positive pressure attack aimed at increasing the safety and effectiveness of firefighting operations.

Abstract. The analysis of the large-scale commercial buildings fires was conducted. The study presents summary of large-scale fires in Mazovian Voivodship in 2015-2016 and its impact on environment. Location and dates of large-scale fires were compared with historical data of air monitoring available on State Inspectorate for Environmental Protection database. Impact of wildfires on environment was already described widely in literature, this approach is focused on commercial buildings fires. The substantial peaks were noticed at Inspectorate for Environmental Protection research stations when large-scale fires occurred, especially regarding fires with long duration. Large fires with short duration were not reflected significantly in air monitoring database.