Radon and its decay products in an air-conditioned auditorium in correlation with indoor air parameters

Abstract

The measurements of radon and its attached decay product activity concentrations were carried out in an occupied and unoccupied auditorium during three air-conditioning modes i.e. air-conditioning system switched off (air-conditioning off), air-conditioning system switched off during the night and switched on during the day (air-conditioning on/off) and air-conditioning system switched on (air-conditioning on). Higher average concentrations of radon and its decay products were recorded in the auditorium when the air-conditioning system was switched off. The average particle mass and CO2 concentrations and indoor air thermal parameters were elevated during the air-conditioning on/off mode. A statistically significant ( p < 0.001) positive correlation between the decay product concentrations and the particle number and average particle mass concentrations has been observed in the air-conditioning off mode ( r = 0.55 and r = 0.68) and in the air-conditioning on/off mode ( r = 0.54 and r = 0.62, respectively). A significant negative correlation has been observed between the decay product concentrations and the indoor air temperature and CO2 concentrations in the air-conditioning off mode ( r = −0.86 and r = −0.47, respectively). The obtained results confirmed the impact of the air-conditioning system operation on the decrease of health risks related to the presence of radon and its decay products in air conditioned premises.