Study on the effect of Fresh Air Ventilation system for reducing indoor 222Rn

Abstract

Objective: To explore the reduction effect for the indoor 222Rn (Rn) by Fresh Air Ventilation (FAV) system, a novel commercial ventilation device in China. Methods: The indoor concentrations of Rn and its decay products (RnD) in three residential rooms, two in Beijing and one in Hefei city, Anhui province, before and after FAVS functioned were measured using an active continuous method. The air exchange rate was monitored by measuring CO2 concentration using the tracer gas method. Results: In the three rooms, the FAVS reduced the Rn concentrations from (162 ​± ​80) Bq/m3 to (63 ​± ​22) Bq/m3 and decreased the RnD concentrations from (64 ​± ​35) Bq/m3 to (13 ​± ​6) Bq/m3 on average, a decrease of (59 ​± ​25)% in the Rn concentrations and a drop of (77 ​± ​18)% in the RnD concentrations. Considering dose conversion factors of Rn and RnD, FAVS decreased the exposure dose by (76 ​± ​20)%. Besides, FAVS increased the air exchange rates from 0.17 h−1 to 0.56 h−1 on average. Conclusions: FAVS can effectively reduce indoor Rn and RnD concentrations by improving the air exchange, serving as a valuable supplement to existing radon mitigation methods, especially in extreme climates.

Keywords

• FAVS
• Rn
• Decay product
• Air exchange rate