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Quantification of Viable Bioaerosol Emanation from an ACMV System and its Impact on Indoor Bioaerosol Pollution

Category: Bioaerosols

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DOI: 10.4209/aaqr.2019.05.0253
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To cite this article:
Xiong, J.W., Wan, M.P., Ng, B.F. and You, S. (2020). Quantification of Viable Bioaerosol Emanation from an ACMV System and its Impact on Indoor Bioaerosol Pollution. Aerosol Air Qual. Res., doi: 10.4209/aaqr.2019.05.0253.

Jin Wen Xiong1, Man Pun Wan 2, Bing Feng Ng2, Siming You3

  • 1 Energy Research Institute @ NTU, Nanyang Technological University, Singapore 637553, Singapore
  • 2 School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798, Singapore
  • 3 School of Engineering, University of Glasgow, Glasgow G12 8QQ, Scotland


  • Pathogenic species from human body (Moraxella) was found in ACMV system.
  • Emanation of ACMV system was the largest contributor to bacteria (2.4 CFU s–1 ).
  • Emanation of ACMV system was the second largest contributor to fungi (3.9 CFU s–1 ).
  • Indoor bacterial concentration can drop by 45% by ACMV cleaning.
  • Indoor fungal concentration can drop by 34% by ACMV cleaning.


Viable bioaerosol can deposit and multiply in air-conditioning and mechanical ventilation (ACMV) systems, eventually entering indoor environments after these systems are operated and contributing to indoor pollution. We propose a method for identifying and quantifying the emanation of viable bioaerosol from an ACMV system and its impact on indoor pollution through surface and air sampling followed by analysis using a material-balance model. Adopting this method, we investigated the contribution of viable bioaerosol from an ACMV system to the indoor pollution in an air-conditioned room located in Singapore. The system, which emanated viable bacteria and viable fungi at the rates of 2.4 CFU s–1 and 3.9 CFU s–1, respectively, was the largest source of indoor viable bacteria and the second largest source of indoor viable fungi (exceeded only by the outdoor fungi introduced through mechanical ventilation) in the air. Potentially pathogenic bioaerosol species in the genera of Staphylococcus, Moraxella and Aspergillus were also identified in the ACMV system. In particular, Moraxella osloensis, the most likely genus to originate from occupants, was found to accumulate in the ACMV system, indicating the potential effect of this system’s cleanliness on indoor pollution. Our method can be used as a tool for analysing the potential sources of indoor bioaerosol and supporting the development of effective control measures for bioaerosol emanation from ACMV systems.


Indoor bioaerosol dynamics Natural ventilation Bacteria Fungi

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