Environmental Engineering Reference
In-Depth Information
chapter five
Biological contaminants —
illness syndromes; bacteria;
viruses; and exposures to insect,
mite, and animal allergens
There is increasing evidence that a significant proportion of illness symptoms
and disease associated with building environments is due to particulate-
phase and, to a much lesser extent, gas-phase exposures to substances pro-
duced by a variety of organisms. These exposures include: airborne mold
(fungi), bacteria and viruses, which may be viable (living) or nonviable;
fragments of bacteria and mold which contain antigens, endotoxins, glucans,
and/or mycotoxins; microbially produced volatile organic compounds; and
immunologically active particles produced by insects, arachnids (mites, spi-
ders), and pets (cats, dogs, etc.).
Contaminants of biological origin such as bacteria, viruses, and fungi
can cause infectious disease by airborne transmission. Exposures to mold
spores/fragments and allergens produced by insects, arachnids, and pet
danders may cause immunological responses such as chronic allergic rhinitis
and asthma. Exposures to high concentrations of small fungal spores and
the spores of the higher bacteria may cause hypersensitivity pneumonitis.
Exposures to fungal glucans, bacterial endotoxins, or microbial volatile
organic compounds (MVOCs) may cause inflammatory responses in the
respiratory system. Mycotoxin exposure may cause severe toxic effects.
Of special concern are those biological contaminants that cause immu-
nological sensitization manifested as chronic allergic rhinitis, asthma, and
hypersensitivity pneumonitis. Chronic allergic rhinitis is an indoor environ-
ment (IE) concern because of its very high and increasing prevalence rate
in developed countries and the similarity of allergy symptoms to those
