Bioaerosol deposition on an air-conditioning cooling coil

Abstract

23This study is concerned with the role of a fin-and-tube heat exchanger in modifying 24 microbial indoor air quality. Specifically, depositional losses of ambient bioaerosols and 25 particles onto dry (not cooled) and wet (cool) coil surfaces were measured for different 26 airspeeds passing through the test coil. Total, bacterial and fungal DNA concentrations in 27 condensate water produced by a wet coil were also quantified by means of fluorescent 28 dsDNA-binding dye and qPCR assays. Results revealed that the deposition of bioaerosols and 29 total particles is substantial on coil surfaces, especially when wet and cool. The average 30 deposition fraction was 0.14 for total DNA, 0.18 for bacterial DNA and 0.22 for fungal DNA 31 on the dry coil, increasing to 0.51 for total DNA, 0.50 for bacterial DNA and 0.68 for fungal 32 DNA on the wet coil. Overall, as expected, deposition fractions increased with increasing 33 particle size and increasing airspeed. Deposited DNA was removed from the cooling coil 34 surfaces through the flow of condensing water at a rate comparable to the rate of direct 35 water over time provides suggestive evidence of biological growth on heat exchangers during 37 nonoperational times of a ventilation system. This investigation provides new information 38 about bioaerosol deposition onto a conventional fin-and-tube cooling coil, a potentially 39 important factor influencing indoor exposure to microbial aerosols in air-conditioned 40 buildings. 41

Systematic characterization and fluorescence threshold strategies for the wideband integrated bioaerosol sensor (WIBS) using size-resolved biological and interfering particles

“…For example, they have been important instruments: in the study of ice nuclei Mason et al, 2015;Twohy et al, 2016), toward the understanding of outdoor fungal spore concentrations (Gosselin et al, 2016;Saari et al, 2015a;O'Connor et al, 2015b), to investigate the concentration and properties of bioaerosols from long-range transport (Hallar et al, 2011), in tropical aerosol Whitehead et al, 2010Whitehead et al, , 2016Huffman et al, 2012;Valsan et al, 2016), in urban aerosol Saari et al, 2015b;Yu et al, 2016), from composting centers (O'Connor et al, 2015b), at high altitude Gabey et al, 2013;Perring et al, 2015;Ziemba et al, 2016), and in many other environments (Healy et al, 2014;Li et al, 2016;O'Connor et al, 2015a). The same instrumentation has been utilized for a number of studies involving the built, or indoor, environment as well (Wu et al, 2016). As a limited set of examples, these instruments have been critical components in the study of bioaerosols in the hospital environment (Lavoie et al, 2015;Handorean et al, 2015) and to study the emission rates of biological particles directly from humans (Bhangar et al, 2016) in school classrooms (Bhangar et al, 2014) and in offices (Xie et al, 2017).…”

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

“…Although non-viable bioaerosols can cause allergies when occupants are exposed to them (Kauffman and van der Heide, 2003), they do not multiply in the environment. The viable bioaerosols can deposit, accumulate, and subsequently multiply on the surfaces of various components of an ACMV system under favourable conditions, exacerbating the biological contamination of the ACMV system (Batterman and Burge, 1995;Siegel and Carey, 2001;Zhao and Wu, 2006;Lu et al, 2009;Bonetta et al, 2010;Chen and Chang, 2012;Schmidt et al, 2012;Wu et al, 2016). These findings indicate the potential of ACMV systems to be bioaerosol emanation sources.…”

Impact of air-conditioning system disinfection on microbial contamination of passenger cars

“…Professional drivers (e.g. taxi and truck drivers) spend on average about 8 h a day in their vehicles (Holmer et al 1995;Jo and Lee 2008;Vonberg et al 2010;Wu et al 2016).…”