The risk of human exposure to finely-dispersed aerosol particles being airborne indoors is determined by the size and the number concentration of particles, the intensity of an aerosol emission source, the air filtration and ventilation efficiency, etc. The emphasis in this article is on behaviour patterns of aerosol particles when exposed to ultrasonic and electrostatic fields in different conditions of air temperature and relative humidity. Wood flour having sizes of interest (characteristic particle diameter about 10 μm) is chosen as a model aerosol. The article considers a physical and mathematical model presenting the evolution of aerosol particles in external fields, taking into account the moisture content and the temperature of a dispersive medium. The efficiency of ultrasonic and electrostatic precipitation in different relative humidity and temperature conditions in an enclosed space was studied using optical measurement methods of particle size and concentration.

Findings. The function of breaking deformations within the rock mass in the bottomhole of a hydromechanical drilling well is dependent on various technological means and methods. A sequential analysis has been conducted to identify the most influential factors in this process. Positive features of hydromechanical drilling have been outlined from the viewpoint of effective intensification of basic technical and economic parameters of the process of well construction with different purposes. Complete operational similarity and technological interconnection of a mechanism of the formation of different parts of a hydromechanical drilling well have been shown in terms of their stipulation by the properties of rock formations and mode support of a well construction process. Top-priority of a hydromechanical drilling type has been proved to generate as many parameters of dynamic effect on rock mass, which results in the increasing scope of bottomhole breaking processes. Attention has been paid to the study of the problem of tool support for drilling operations from the viewpoint of tracing the nature of bottomhole processes running in terms of different technical and technological factors. The possibility and necessity of using surface-active substances (SAS) as the main activators of positive deformation interactions in the “metal pellets – rock” pair have been proved and substantiated; use will be based on the developed methodological approaches of rational selection of a component-concentration composition of a breaking medium.
Originality. The efficiency of a hydromechanical drilling type is stipulated by the degree of dynamic effect on the rock bottomhole; depending on its geological-mineralogical and physicomechanical features, it can be intensified by increasing frequency of impacting, interpretation of the effecting mechanism, variation of the cleaning agent type as well as directed activation of the manifestation of surface and interphase interactions.
Practical implications. The represented results of analytical and laboratory-experimental studies are the basis for the development of methodological foundations to elaborate the mode parameters of the technology of hydromechanical drilling for the construction of wells. They belong to the basic initial data applied while developing the design and working characteristics of the corresponding modernised operating members.