Environmental Health Criteria 214

HUMAN EXPOSURE ASSESSMENT
Spore counts can vary greatly indoors for several reasons
including the presence of colonizing fungi. Fig. 29 illustrates this
point. The figure shows the mean values of CFU per culture plate for
four fungal taxa and all others collected during the summer in nine
Portage, Wisconsin (USA) homes. Living room and bedroom samples
reflect the taxa found outdoors. The basement samples show
Penicillium and Aspergillus fungi which grow favourably in damp
areas (Burge, 1990).
In addition physical activity, such as vacuuming, starting an
air-conditioning fan, children playing on a carpet or changing a
filter, might raise spore concentrations by a factor of 10 or more.
Even without mechanical disruption, periodic shedding or ejection of
spores from growing fungi might similarly elevate concentrations.
9.5 Bacteria (including actinomycetes)
Bacteria are prokaryotic cells. Certain bacteria are infectious
and can be transmitted by air and contact, including ingestion. Common
contagious airborne diseases include tuberculosis and some forms of
pneumonia. Other diseases, such as legionellosis from water,
respiratory infections from Pseudomonas in humidifiers and several
others from handling animals are not transmitted from person to
person.
Sampling and identifying specific bacteria is very important in
many settings, especially in hospitals with immune-compromised and
immune-suppressed patients. There are numerous other situations where
infectious diseases have been transmitted by airborne bacteria. These
include tuberculosis transmission in aircraft, and Legionella
transmission in hospitals, in hotels, in supermarkets and on cruise
ships or even in buildings in locations affected by cooling tower
mist. The two approaches available to measure the presence of bacteria
as indicators of exposure are sampling of air and sampling of soil,
dust or water.
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