Most people spend the majority of their time in indoor environments where the level of harmful pollutants is often significantly higher than outdoors. Radon (222Rn) and its decay products are the example of radioactive pollutants. These radioisotopes are the main source of ionizing radiation in non-industrial buildings. The aim of the study was to determine the impact of air-conditioning system on radon and its progeny concentrations and thus on the effective dose. The measurements were carried out in the auditorium at the Environmental Engineering Faculty (Lublin University of Technology, Poland). Measurements of radon and its progeny (in attached and unattached fractions) as well as measurements of the following indoor air parameters were performed in two air-conditioning (AC) operation modes: AC ON and AC ON/OFF. The air supply rate and air recirculation were taken into consideration. The separation of radon progeny into attached and unattached fractions allowed for determining, respectively, the dose conversion factor (DCF) and the inhalation dose for teachers and students in the auditorium. A considerable increase of the mean radon progeny concentrations from 1.2 Bq/m3 to 5.0 Bq/m3 was observed in the AC ON/OFF mode compared to the AC ON mode. This also resulted in the increase of the inhalation dose from 0.005 mSv/y to 0.016 mSv/y (for 200 h/year). Furthermore, the change of the air recirculation rate from 0% to 80% resulted in a decrease of the mean radon concentration from 30 Bq/m3 to 12 Bq/m3 and the reduction of the mean radon progeny concentration from 1.4 Bq/m3 to 0.8 Bq/m3. This resulted in the reduction of the inhalation dose from 0.006 mSv/y to 0.003 mSv/y.
National Atomic Energy Agency. (2015). Annual report on the activities of the President of the National Atomic Energy Agency and assessment of nuclear safety and radiological protection in Poland in 2014. Warszawa: Państwowa Agencja Atomistyki (in Polish).
Kozak, K., Mazur, J., Kozlowska, B., Karpińska, M., Przylibski, T. A., Mamont-Cieśla, K., Grządziel, D., Stawarz, O., Wysocka, M., Dorda, J., Żebrowski, A., Olszewski, J., Hovhannisyan, H., Dohojda, M., Kapała, J., Chmielewska, I., Kłos, B., Jankowski, J., Mnich, S., & Kołodziej, R. (2011). Correction factors for determination of annual average radon concentration in dwellings of Poland resulting from seasonal variability of indoor radon. Appl. Radiat. Isot., 69, 1459–1465.
Somlai, J., Jobbágy, V., Kovács, J., Németh, Cs., & Kovács, T. (2008). Connection between radon emanation and some structural properties of coal-slag as building material. Radiat. Meas., 43(1), 72–76.
Kovler, K. (2012). Does the utilization of coal fly ash in concrete construction present a radiation hazard? Constr. Build. Mater., 29, 158–166.
Połednik, B., Dudzińska, M. R., Kozak, K., Mazur, J., & Gazda, L. (2012). The impact of the indoor air parameters on the dynamics of radon and its decay products concentration changes. In Proceedings of Healthy Building, 8–12 July 2012 (pp. 2B.8). Brisbane, Australia.
Kávási, N., Kovács, T., Németh, C., Szabó, T., Gorjánácz, Z., Várhegyi, A., Hakl, J., & Somlai, J. (2006). Difficulties in radon measurements at workplaces. Radiat. Meas., 41, 229–234.
Marley, F., & Phillips, P. S. (2001). Investigation of the potential for radon mitigation by operation of mechanical systems affecting indoor air. J. Environ. Radioact., 54, 205–219.
Karpińska, M., Mnich, Z., & Kapała, J. (2004). Seasonal changes in radon concentrations in buildings in the region of northeastern Poland. J. Environ. Radioact., 77(2), 101–109.
Moriizumi, J., Yamada, S., Xu, Y., Matsuki, S., Hirao, S., & Yamazawa, H. (2014). Indoor/outdoor radon decay products associated aerosol particle-size distributions and their relation to total number concentrations. Radiat. Prot. Dosim., 160(1/3), 196–201. .
Darby, S., Hill, D., Auvinen, A., Barros-Dios, J. M., Baysson, H., Bochicchio, F., Deo, H., Falk, R., Forastiere, F., Hakama, M., Heid, I., Kreienbrock, L., Kreuzer, M., Lagarde, F., Mäkeläinen, I., Muirhead, C., Oberaigner, W., Pershagen, G., Ruano-Ravina, A., Ruosteenoja, E., Rosario, A. S., Tirmarche, M., Tomásek, L., Whitley, E., Wichmann, H. E., & Doll, R. (2005). Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies. Br. Med. J., 330, 223–227.
Ramola, R. C., Negi, M. S., & Choubey, V. M. (2003). Measurement of equilibrium factor “F” between radon and its progeny and thoron and its progeny in the indoor atmosphere using nuclear track detectors. Indoor Built Environ., 12, 351–355.
Forkapić, S., Mrđa, D., Vesković, M., Todorović, N., Bikit, K., Nikolov, J., & Hansman, J. (2013). Radon equilibrium measurement in the air. Rom. J. Phys., 58, S140–S147.
UNSCEAR. (2000). United Nations Scientific Committee on the Effect of Atomic Radiation exposures from natural radiation sources. Report to General Assembly. Annex B. New York: UN.
Kozak, K., Grządziel, D., Połednik, B., Mazur, J., Dudzińska, M. R., & Mroczek, M. (2014). Air conditioning impact on the dynamics of radon and its daughters concentration. Radiat. Prot. Dosim., 162(4), 663–673.
Nero Jr, A. V. (1988). Radon and its decay products in indoor air – an overview. In W. W. Nazarov, & A. V. Nero (Eds.), Radon and its decay products in indoor air (pp. 1–53). New York: Wiley Interscience.
Porstendörfer, J. (1996). Radon: measurements related to dose. Environ. Int., 22(Suppl. 1), S563–S583.
Bennett, W. D., Zeman, K. L., & Jarabek, A. M. (2003). Nasal contribution to breathing with exercise: effect of race and gender. J. Appl. Physiol., 95(2), 497–503.