Atmospheric Pollution Research 5 (2014) 431‐437 © Author(s) 2014. This work is distributed under the Creative Commons Attribution 3.0 License. A Atm spheric P Pollution R Research www.atmospolres.com Workplace personal exposure to respirable PM fraction: a study in sixteen indoor environments Dikaia E. Saraga 1 , Lefteris Volanis 2 , Thomas Maggos 1 , Christos Vasilakos 1 , Kyriaki Bairachtari 1 , Costas G. Helmis 2 1 Environmental Research Laboratory, INRASTES, National Center for Scientific Research "DEMOKRITOS", Aghia Paraskevi Attikis, P.O.B. 60228, 15310 Athens, Greece 2 Department of Environmental Physics and Meteorology, Faculty of Physics, University of Athens, University Campus, building PHYS‐5, 157‐84 Athens, Greece ABSTRACT The present paper focuses on respirable particulate matter (RPM) measurements conducted at the breathing zone of adult volunteers in sixteen different working environments: two offices, a house, a chemical laboratory, a non– smoking shop, a pharmacy store, a car garage, a hairdresser’s store, a photocopy store, a taxi, a gym, a mall, a restaurant, a bar, a kiosk and a school. The sixteen different cases were categorized according to the location, the type of the activities taking place indoors, the number of occupants, the proximity to heavy traffic roads, the ventilation pattern etc. According to the results, the maximum particle concentration (in average 285 μgm –3 ) was recorded at the hairdresser store while the minimum concentration was measured in the cases of the housewife and the employee in the non–smoking shop (in average 30 μgm –3 ). The results indicated smoking as a factor which strongly influences the exposure levels of both smokers and passive smokers. Furthermore, it was found that the building ventilation pattern comprises an important factor influencing the exposure levels especially in cases of buildings with great number of visitors (resuspension) and smoking. Keywords: Exposure, respirable particles, working places, ventilation rate Corresponding Author: Dikaia E. Saraga  : +30‐210‐6503719  : +30‐210‐6525004  : dsaraga@ipta.demokritos.gr Article History: Received: 09 October 2013 Revised: 05 March 2014 Accepted: 05 March 2014 doi: 10.5094/APR.2014.050 1. Introduction The term of respirable particulate matter (RPM) refers to the suspended particle fraction with aerodynamic diameter smaller than 4 micrometers (OSHA–Occupational Safety and Health Administration). Personal exposure is the concentration measured near the breathing zone, integrated over a specified time period and varies as a person moves from one microenvironment to another. Although indoor air constitutes only a small fraction of the planet’s atmosphere, it occupies the majority of the respirable human air fraction, as people spend almost 90% of their time in indoor environments. It is noteworthy that for many individuals, average exposures to particulate matter (PM) show higher correlation with indoor than ambient PM concentrations (Chow et al., 2002). Furthermore, studies have proved that most chemical substances, to which people are exposed every day (such as particulate matter), constitute an additional risk factor in the development of several pathologies (Guo et al., 2003; Sundell, 2004; Pilou et al., 2010; Moghaddasi et al., 2014). For instance, exposure to particles originated from indoor combustion sources as tobacco smoke (Hackshaw et al., 1997) has been associated to increased mortality and morbidity from lung cancer and other diseases. Several studies have reported significant health risks associated with exposure to particulate matter (Pope et al., 2002; Pope and Dockery, 2006; Ashok et al., 2014). During the last decades, research works have studied the relationship between indoor and outdoor concentrations of different air pollutants, in various microenvironments (Chaloulakou et al., 2003; Long and Sarnat, 2004; Lai et al., 2006; Sarnat et al., 2006; Jones et al., 2007; Halios et al., 2009; Siddiqui et al., 2011; Buonanno et al., 2014). Indicatively, EXPOLIS project aimed at studying adult exposure to PM 2.5 in the city of Helsinki, concluding that active smokers were exposed to almost double levels than those of passive smokers exposed to environmental tobacco smoke (ETS) and three times those of participants not exposed to tobacco smoke (Koistinen et al., 2001). In another study, measurements of commuter and driver exposure to aerosol particles were conducted in buses and trams in Helsinki (Asmi, 2009). Berghmans et al. (2009) have studied and estimated the exposure of a cyclist to particles of various size fractions including ultrafine particles (UFP) in the town of Mol, Belgium. The major sources of UFP and PM 10 were identified as vehicular emission and construction activities, respectively. Indoor and outdoor ultrafine particles (UFPs) concentration levels were examined in the area of Athens during the cold period of 2003 and 2004 by Diapouli et al. (2007) who indicated outdoor environment, smoking, cleaning activities and the large amount of people in a small place as the main sources of UFPs. The present study focuses on the comparison of respirable particle levels measured in sixteen different workplaces in a big European city, Athens. Parameters as the buildings location, the type of the activities taking place indoors, the number of