in air the first process is ozone generation due to dissociation of oxygen molecule into two atoms the length of life of non associated oxygen atoms is short and if ozone moves along the discharge electrode instead of being removed from it a second chemical process i e ozone dissociation occurs another advantage of the discharge electrode axis coincidence with the airflow direction is zero contamination of the discharge electrode the reason is that during charging dust particles are removed from the discharge electrode in order to achieve another objective of the invention i e to improve the efficiency of dust collection without increasing the length of the entire electrostatic filter in the proposed invention the airflow direction is changed at least once by an angle of more than 135 u00b0 in this approach the dust collection process may be multistage moreover in each following stage the dust collection is effected in airflow whose direction is altered by an angle of more than 135 u00b0 relatively to the previous stage in the proposed invention the first operation of dust collection is also separated from the dust charging operation by an operation of airflow direction change by an angle of more than 135 u00b0 which enables to determine the length of the electrostatic filter such that it will be equal to that required for dust charging operation the electrostatic filter of the present invention that realizes the advantages of the method of the present invention includes a dust charging device a device for at least.