bioaerosol

A bioaerosol is any airborne particle of biological origin. This includes bacteria, viruses, fungal spores, pollen, and fragments of plant or microbial material, as well as microbial metabolites. Bioaerosols can be alive or inactivated and vary widely in size, from tens of nanometers to tens of micrometers, with many particles small enough to be inhaled into the deeper parts of the respiratory tract.

Common sources of bioaerosols include humans and other animals, soil, water, and plants. They can be emitted directly from living organisms or released as fragments and byproducts such as allergenic proteins or endotoxins. Particle size influences transport, deposition, and viability; fine fractions tend to stay suspended longer and can reach the lower airways, while larger particles may settle more quickly.

Exposure to bioaerosols occurs primarily through inhalation and can lead to a range of health effects. Allergic reactions and asthma are common responses to pollen and fungal spores, while infections can occur from viable bacteria and viruses, particularly in immunocompromised individuals. The health impact depends on factors such as particle size and concentration, duration of exposure, environmental conditions, and the host’s immune status.

Measurement and analysis of bioaerosols employ various sampling methods, including active samplers (such as impactors, filters, impingers, and cyclones) and passive approaches, followed by culture-based, microscopic, or molecular analyses (for example, PCR). Reported metrics include colony-forming units per cubic meter (CFU/m3) and particle concentrations.

In indoor environments, bioaerosols contribute to occupants’ comfort and health; controls emphasize adequate ventilation, high-efficiency filtration (for example, HEPA), humidity management, and source reduction. Outdoor bioaerosol levels are influenced by seasonal patterns and weather.