Indoor bioaerosol dynamics

Nazaroff, William W

A few recent studies have aimed to quantify sizeresolved biological particle emission rates associated with human occupants using modern analytical methods. Qian et al. (2012) studied a university classroom with bioaerosol sampling using a cascade impactor followed by quantitative PCR applied with universal bacterial and fungal primers. By applying material balance to the indoor and outdoor data under room-occupied and unoccupied conditions, they inferred the per-occupant effective emission rates of bacteria and fungi. For example, the bacterial emission rates were determined to average 37 million genome copy numbers per hour per occupant. Particle size conformed reasonably well to a lognormal distribution with a geometric mean aerodynamic diameter of 4.4 lm and a geometric standard deviation of 1.39. Bhangar et al. (2014) used realtime particle detection to quantify size-resolved emissions of fluorescent biological aerosol particles also in a university classroom. They concluded that the modal size was in the range 3-4 lm and that the average emission rates were 1.6 million particles per person per hour during the main portion of lecture classes plus 0.8 million particles per person emitted during transitions between classes.