Abstract: Radon in the air is mainly released from the rock and soil radon. The geochemical characteristics of radon in soil gas around the Capital area of China were investigated based on the measurements of radon concentrations in Sanhe area, Yanhuai basin and Tangshan area. The mean radon concentrations were 2×10⁴-2.5×10⁴, 1.5×10⁴-2×10⁴, and less than 1.5×10⁴ Bq·m^-3in Sanhe area, Tangshan area, and Yanhuai basin, respectively. Overall, the distribution of radon concentration was higher in the east than in the west. Based on the soil radon concentration in the international environmental hazard classification, some parts of the study areas reached to the moderate risk level. Based on China’s standards (code for indoor environmental pollution control of civil building engineering), anticracking and waterproof measures should be taken on the ground floors of buildings in Sanhe area and Tangshan area, while no measures are needed to prevent radon in Yanhuai basin.

Key words: footprint size, three-dimensional ecological footprint, natural capital, footprint depth, Shenyang