ABSTRACT
Bioaerosols are those airborne particles that originated from living organisms (e.g., bacteria, protists, plants, fungi, and animals) or that depend on living organisms (e.g., viruses). Bioaerosols may consist of entire microscopic structures, for example, viruses, intact bacterial cells and spores, protozoa and their cysts, fungal cells and spores, and plant pollen grains and spores. Cell fragments may be present in indoor and outdoor air and are also considered bioaerosols, for example, airborne particles of decayed microbial, plant, and animal matter; wood and grain dusts; the droppings and dried body parts of arthropods; and particles of larger animal skin, saliva, feces, and urine. The term biological agent refers to any substance of biological origin that is capable of producing an effect on humans, for example, infectious agents, bacterial DNA, peptidoglycans, endotoxin, exotoxins, mycotoxins, and (1 → 3)-β-d-glucans and allergens from bacteria, pollen, fungi, dust mites, cockroaches, and so forth. Bioaerosols may elicit responses similar to those caused by nonbiogenic particles (e.g., a hypersensitivity, irritant, or inªammatory response) as well as unique reactions (e.g., infectious diseases and toxicoses). The respiratory tract responds to injury, including that caused by biological agents, in a limited number of ways, for example, rhinosinusitis, pharyngitis, laryngitis, upper airway obstruction, alveolitis, pulmonary edema, asthma, chronic obstructive pulmonary disease (COPD), bronchitis, and pulmonary infection.1 Bioaerosols occur as airborne particles in a size range of ∼0.02-100 μm; thus, different cells, spores, pollen grains, and biological fragments may deposit in all regions of the human airways. Smaller bioaerosols remain airborne for longer periods and travel further distances, which makes it possible for one person in a shared space to expose a large number of individuals to an infectious agent. Microorganisms, plants, and animals are important components of surface waters and soil. Although not particulate in form, plants and animals release gases and vapors, for example, oxygen, carbon dioxide, methane, and water. Emissions from microorganisms (microbial volatile organic compounds [MVOCs]) account for the earthy smell that follows a rain shower or comes from freshly turned garden soil. The distinctive ªavors of certain foods and beverages as well as the less pleasant aromas of decay, body odor, and moldy buildings are also volatile microbial metabolites. The complex interactions of MVOCs and bioaerosols with other airborne particles are seldom studied but are likely important for a comprehensive understanding of the effects of biological agents on human health and comfort. While it is impossible to cover this broad topic in great depth in a single chapter, we discuss health effects, dosimetry, and bioaerosol measurement with illustrations and examples from the vast literature on the subject.
