FIELD: evaluation of radio hazard over territories in the course of engineering-ecological investigations. SUBSTANCE: volumetric activity of radon is simultaneously measured in two points located at distance from 0.2 to 1.0 m one from another. Measurement depth h1 of one point is from 0.2 to 0.5 m and measurement depth of the other point is h2 = 2h1,. Thereupon density of flow of radon is found. EFFECT: simplified procedure and raised authenticity of it.
