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

Abstract

Viable bioaerosols can deposit and multiply in airconditioning and mechanical ventilation (ACMV) systems. These bioaerosols can eventually enter indoor environments following the operation of the ACMV systems, contributing to indoor bioaerosol pollution. A method to identify and quantify viable bioaerosol emanation from an ACMV system and its impact on indoor bioaerosol pollution is proposed in this study. The method involves surface and air sampling of viable bioaerosols with analysis using a material-balance model. The proposed method was adopted to investigate the contribution of viable bioaerosol emanation from an ACMV system to indoor bioaerosol pollution in an air-conditioned room located in Singapore. The bioaerosol emanation rates from the ACMV system were found to be 2.4 CFU s-1 for viable bacteria and 3.9 CFU s-1 for viable fungi. Among various bioaerosol sources, bioaerosol emanation from the ACMV system was the largest source of indoor viable bacteria and the second largest source of indoor viable fungi in the air, behind the introduction of outdoor fungi through the mechanical ventilation. Potentially pathogenic bioaerosol species were also found in the ACMV system, which are in the genera of Staphylococcus, Moraxella and Aspergillus. Particularly, Moraxella osloensis, which is most likely to be emanated from occupants, was found to accumulate in the ACMV system, indicating the potential impact of the ACMV system's hygiene on indoor bioaerosol pollution. This study could contribute to the understanding of bioaerosol emanation from ACMV systems and their impact on indoor bioaerosol pollution. The proposed method could be used as a tool for analysing the potential sources of indoor bioaerosols and support the development of effective control measures against bioaerosol emanation from ACMV systems.

Recent advances in the application of ionic liquids in antimicrobial material for air disinfection and sterilization

“…The concept of airborne transmission, also known as aerosol transmission, has gained prominence in recent decades due to frequent outbreaks of epidemic diseases. Unlike the traditional understanding of air pollution caused by inorganic particles or noxious gases, the study of aerosols investigates the effect of bioactive or infectious particles such as viruses, bacteria, or fungi, which can be suspended in air for not only a short distance as droplets, but also a long-range travel as air mass and have a strong influence on respiratory system ( Figure 1 ) ( Duchaine and Roy, 2022 , 154117; Mutuku et al., 2020 , 1172–96; Morawska et al., 2020 , 105832; Jeong et al., 2022 , 100182; Xiong et al., 2020 , 762–75). With modern lifestyles resulting in an ever-increasing amount of time spent indoors and the unavoidable production of aerosols from breathing, talking, coughing, flushing toilets, etc., the best way to protect the public from infectious aerosol is to sterilize the air through the daily use of heating, ventilation, and air conditioning (HVAC) systems.…”

“…Reproduced with permission from Elsevier Ltd. ( Jeong et al., 2022 , 100182); (E) Identified bacterial and (F) fungal species emanated from the Air Conditioning and Mechanical Ventilation System. Reproduced with permission from ( Xiong et al., 2020 , 762–75).…”

“…Unfortunately, most commercial HVAC systems and portable devices are not equipped with disinfection capabilities. Furthermore, the accumulation of dust containing bioactive pathogens can create a source of contamination, thus increasing the risk of infection ( Xiong et al., 2020 , 762–75). Portable devices can be designed to be disposable, but the short lifespan and the health risks of respiratory irritation posed by antimicrobial agents, such as ozone and chlorides, currently impede their widespread use ( Bruchard et al., 2021 , A35D-1662; J.…”