The Influence of the Equilibrium Factor on the Estimated Annual Effective Dose From Inhaled Radon Decay Products in Selected Workplaces

Abstract

Measurements of activity concentration of radon gas and radon decay products were carried out in several workplaces including schools, radium spas, swimming pools, water treatment plants, caves and former mines. Based on these measurements, annual effective doses to workers were estimated and values of the equilibrium factor, F, were calculated. This paper describes the different approaches used to estimate the annual effective dose based on the dose coefficients recommended by the International Commission on Radiological Protection. Using the measured F values as opposed to the default F value of 0.4 changed the doses by about 5–95% depending mainly upon the ventilation conditions of the workplace.

Modeling: Activity Concentration of Radon, Thoron, and Their Decay Products in Closed Systems

“…According to the ICRP report [ 10 ], the equilibrium factors for a reference worker (average breathing rate of 1.2 m 3 /h) are equal to 0.4 in indoor workplaces, 0.2 in mines, and 0.4 in tourist caves. As has been shown in different studies, the equilibrium factors can differ considerably from the values mentioned above [ 12 , 13 , 14 ], especially when mechanical ventilation is applied. According to a comprehensive study carried out by Chen and Harley [ 12 ], the equilibrium factors varied from 0.08 to 0.72 for active mines in 18 countries and from 0.10 to 0.85 for caves, tourist mines, and thermal spas.…”