When the over pressure of a blast wave is calculated and its effects on valuated objects are set, many approximations are used. Basic relationships, used to calculate the maximum blast overpressure, safety distances and building damage, are created for industrial accidents or for objects where explosives and munitions are stored. This method is invalid in public spaces. More than 95% of all terrorist attacks are carried out using ANFO (ammonium nitrate -fuel oil) explosives in three different variants (ammonium nitrate with oil, ammonium nitrate with oil and aluminium powder or ammonium nitrate with oil and trinitrotoluene (TNT)).The commonly used method to calculate the overpressure uses a scaled distance. The value of the scaled distance is derived from heat created by combustion. A theoretical value for the combustion heat of an industrialproduced ANFO explosion does not represent the real history of explosion or the size of overpressure. For example, the heat of combustion of Slovak-produced DAP-E is the same as TNT. From the relationship used, it emerges that the explosions have the same capacity. We have conducted more than 130 field tests of the ANFO explosive, where the history of blast wave was recorded. The results of the measurements clearly show the invalidity of this theory. The values of the calculated and measured overpressure are significantly different. It is necessary to choose a different approach for the TNT equivalent method. In the first part of this paper, we present the results of the conducted field tests. The experimental results are analysed using commonly-used methods. At the end of our paper we present a new relationship, used to calculate the maximum blast overpressure, which is based on the measured overpressure. This paper presents the results of scientific research at the Faculty of Special Engineering, University of Zilina.

The purpose of the paper is to investigate the influence of geometry of charges on the propagation of blast waves. Various shape charges (cylinder, sphere, irregular shape) were used in the field tests. The main type of explosive, homemade ANFO (Ammonium nitrate + fuel oil), was used as the most common used explosives in improvised explosive devices used in terrorist attacks. Characteristics of homemade and industrially made ANFO explosives are different. There were comparing charges of various types of industrially produced types of explosives and homemade explosive in the field tests. The blast wave propagation were investigated and compared. Keywords: ammonium nitrate and fuel oil explosives, blast pressure, blast wave, blast wave propagation, field test.

The paper deals with the possibility of the population treat during cultural and social events. There is a great availability of resources and processes for the production of explosives. The paper is focused on the using of explosives, the blast wave arising in the explosion and its impact on the environment. In the fi nal part there is described the effects of the explosion on the human body.