The application of diffusive uptake rates of selected volatile organic compounds on tubes for investigating the air exchange rate in dwellings

Introduction The specific geological bedrock in the Czech Republic causes one of the highest levels of radon exposure in the world. The current Czech National Action Plan, based on the WHO 2005 directive on the reduction of radon exposure in workplaces and homes, covers the monitoring of the non-exceedance of the reference level of 300 Bq m −3 in relevant buildings, including the determination of the average air exchange rate (AER). Methods A dual-tracer source–sorbent tube system was designed to determine the average AER over the measurement period, ranging from a few days up to 1 month. This system aims to create a cost-effective method for application in houses on a national level. AER assessment and simultaneous radon gas measurements enable the estimation of the behavior of radon entry rate into the buildings. The system based on the use of multiple tracer gases also allows the estimation of inter-compartment airflows between individual floors of measured multi-story buildings. The average AER in a building is calculated from the known weight difference of the container filled with suitable volatile organic compounds (VOCs), the amount of the tracer adsorbed on a tube determined by a gas chromatography system, the temperature, time exposure in a dwelling, and the uptake rate for specific sorbent and VOC tracer. Results The total uncertainties of the AER measured in the field were around 15%, and the inter-compartment airflows, which were typically of the order of units of m 3 h −1 , ranged from 30% to 60%, with a coverage factor of k = 1. The exposure time influence in correlation with temperatureinfluence of the uptake rates for a PFT—Carbopack B™ systemwas assessed during measurement in the radon chamber. Discussion The main outcome of the method developed is to provide customers, from the relevant field of building and thermal engineering or indoor air and radiation hygiene, an independent result of the measurement of the AER which has a key influence on heat loss in buildings and the behavior of all indoor pollutants in gaseous and aerosol form.