The most frequent defects
in quality derive from inadequate ventilation,
pollution generated inside the building and contamination
from exogenous origin. When more
than 20% of the occupants of a building complain
about the quality of the air or show clear symptoms
of drowsiness, fatigue, nausea, cough,
asthma or related respiratory disorders, the phenomenon
is known as the “sick building syndrome”.
In general, predominant bacteria in indoor
air are gram-positive and usually not dangerous
for human health but, because they often derive
from the skin and the respiratory tract of occupants,
high viable counts are used as markers of
crowded conditions and poor ventilation.