Short-term dynamic patterns of bioaerosol generation and displacement in an indoor environment

Abstract

The short-term dynamics and distribution of airborne biological and total particles have been assessed in a large university hallway by particle counting using laser particle counters and impaction air samplers. Particle numbers of four different size ranges were determined every 2 min over several hours. Bioaerosols (culturable bacteria and fungi determined as colony-forming units) were directly collected every 5 min on Petri dishes containing the appropriate growth medium. Results clearly show distinct short-term dynamics of particulate aerosols, of both biological and non-biological origin. These reproducible periodic patterns are closely related to periods when lectures are held in lecture rooms and the intermissions in between when students are present in the hallway. Peaks of airborne culturable bacteria were observed with a periodicity of 1 h. Bioaerosol concentrations follow synchronously the variation in the total number of particles. These highly reproducible temporal dynamics should be considered when monitoring indoor environments to determine air quality.

Bioaerosols in Indoor Environment - A Review with Special Reference to Residential and Occupational Locations

“…The number of culturable fungi correlated well with total number of particles <2.5 m [6]. However, other studies showed that also bacterial numbers are only correlated to size rages of 1 to 5 m and >5 m [56].…”

“…1 to 5 m) and the number of fungal or bacterial colony forming units [55][56][57][58]. Particle counting can be done on a fast basis (using appropriate equipment) without the need of applying air sampling and microbial identification techniques (e.g.…”

“…Several broad spectrum media have been evaluated for culturable airborne fungi such as malt extract agar, Rose Bengal agar and DG-18 agar [33,[67][68][69]. For the cultivation of bacteria, several broad spectrum media such as tryptic soy agar or nutrient agar are commonly used [27,56]. It has to be stressed, however, that only a small fraction of airborne microbes in a sample can be cultivated, resulting in numbers usually one or two orders less than determined by cultivation-independent methods [70].…”

“…Laser particle counters are used to determine particle numbers [55,56]. Particle size determination is based on optical particle counting by light scattering (refraction, reflection, and diffraction) from single particles flowing out of a nozzle.…”

Assessment of Indoor Bioaerosols in Public Spaces by Real-Time Measured Airborne Particles

“…Long-term exposure to indoor environments with inadequate air exchange and poor air quality may cause sick building syndrome (SBS), allergic reactions, respiratory tract infection, and lung cancer (Dales et al, 2008;Joshi, 2008;Sidra et al, 2015). Bioaerosols are suspended biological particles consisting of microorganisms or organism-derived materials (Douwes et al, 2003;Brandl et al, 2008). Indoor airborne biological pollutants have numerous sources, including outdoor air, human bodies, wallpaper, carpet, resuspended particles, air conditioning systems, and animal waste (Lindemann et al, 1982;Pastuszka et al, 2000;Chao et al, 2002;Hargreaves et al, 2003;Kalogerakis et al, 2005;Tseng et al, 2011;Hospodsky et al, 2012;Xu et al, 2017).…”