The impact of recirculation,ventilation and filters on secondary organic aerosols generated by indoor chemistry |
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| Authors: | MO Fadeyi CJ Weschler KW Tham |
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| Institution: | 1. Department of Building, School of Design and Environment, National University of Singapore, SDE 1, 4 Architecture Drive, Singapore 117566, Singapore;2. International Centre for Indoor Environment and Energy, Technical University of Denmark, Building 402, DK-2800 Lyngby DK, Denmark;3. Environmental and Occupational Health Sciences Institute, UMDNJ/Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ 08854, USA;1. Department of Architecture, School of Design, Shanghai Jiao Tong University, Shanghai, 200240, China;2. Tianjin Key Laboratory of Indoor Air Environmental Quality Control, School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072, China;1. Institute of Mathematics and Physics, Aberystwyth University, Aberystwyth SY23 3BZ, UK;2. Department of Computer Science, Swansea University, Swansea SA2 8PP, UK;1. Institut National de l''Environnement Industriel et des Risques (INERIS), Verneuil-en-Halatte, France;2. IRCELYON, Institut de Recherches sur la Catalyse et l''Environnement de Lyon, UMR5256, Villeurbanne, France;3. Centre Scientifique et Technique du Bâtiment (CSTB), Grenoble, France;1. Department of Mechanical and Information Engineering, University of Seoul, Seoul 02504, Republic of Korea;2. Department of Computational Science and Engineering, Yonsei University, Seoul 03722, Republic of Korea |
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| Abstract: | This study examined the impact of recirculation rates (7 and 14 h?1), ventilation rates (1 and 2 h?1), and filtration on secondary organic aerosols (SOAs) generated by ozone of outdoor origin reacting with limonene of indoor origin. Experiments were conducted within a recirculating air handling system that serviced an unoccupied, 236 m3 environmental chamber configured to simulate an office; either no filter, a new filter or a used filter was located downstream of where outdoor air mixed with return air. For otherwise comparable conditions, the SOA number and mass concentrations at a recirculation rate of 14 h?1 were significantly smaller than at a recirculation rate of 7 h?1. This was due primarily to lower ozone concentrations, resulting from increased surface removal, at the higher recirculation rate. Increased ventilation increased outdoor-to-indoor transport of ozone, but this was more than offset by the increased dilution of SOA derived from ozone-initiated chemistry. The presence of a particle filter (new or used) strikingly lowered SOA number and mass concentrations compared with conditions when no filter was present. Even though the particle filter in this study had only 35% single-pass removal efficiency for 100 nm particles, filtration efficiency was greatly amplified by recirculation. SOA particle levels were reduced to an even greater extent when an activated carbon filter was in the system, due to ozone removal by the carbon filter. These findings improve our understanding of the influence of commonly employed energy saving procedures on occupant exposures to ozone and ozone-derived SOA. |
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