Transport Mechanisms of Bioaerosols

The dominant factors influencing the movement and behavior of bioaerosols in indoor settings are airflow patterns, ventilation strategies, humidity, and temperature. These factors play a significant role in the dispersion, suspension, and settlement of bioaerosols, and it is in turn critical to the indoor air quality and health safety overall. Laminar and turbulent flows determine bioaerosol distribution. Unlike laminar flow, which can concentrate contaminants, turbulent flow disperses them, particularly in narrow rooms. Walls and furniture may create niches where bioaerosols accumulate. Positive- and negative-pressure systems are applied in areas that demand bioaerosol containment or exclusion, such as in hospitals and laboratories. Positive-pressure rooms force the air outside to exclude the contaminants, whereas the negative-pressure rooms force the air in to enclose the bioaerosols in rooms that might be infected. Relative humidity (RH) has a significant effect on the stability and behavior of bioaerosols. Moisture in the air may increase the weight of bioaerosols and thus enhance their settling velocity, but it may also improve microbial survival time. On the other hand, low RH dries the particles, reduces viability, but increases resuspension due to the light particles. Temperature also influences the characteristics of bioaerosols. When the weather is warmer, bioaerosols are more buoyant, so the particles stay in the air longer. When the weather is colder, condensation occurs, attaching particles to the surface.