Indoor
air quality problems are recognized as important risk factors for
human health.
In
residences, day-care centers, retirement homes and other special
environments, indoor air pollution can affect susceptible groups
that may be vulnerable due to their health status or age.
Microbial contamination can involve thousand of species of bacteria
and fungi that grow indoors when sufficient moisture is available.
Exposure to this microbial contamination is clinically associated
with respiratory symptoms, allergies, asthma and immunological
reactions. The indoor environment plays a special role as a health
determinant, and management of indoor air quality requires
approaches that differ from those used for outdoor air.
There
is strong evidence regarding the hazards posed by several
biological agents that pollute the indoor air; however, the WHO working group convened in October 2006
concluded that the individual species of microbes and other
biological agents that are responsible for health effects could not
be identified. This is due to people often being exposed to
multiple agents simultaneously, to complexities in accurate
estimation of exposure and to the large numbers of symptoms and
health outcomes due to exposure. The exceptions include some common
allergies, which can be attributed to specific agents, such as
house dust mites and pets.
The
presence of many biological agents in indoor environments is
attributable To dampness and inadequate ventilation. Excess
moisture on almost all indoor materials leads to the growth of
microbes, such as mold and bacteria, which subsequently emit
spores, cells, fragments and volatile organic compounds into the
indoor air. Moreover, dampness initiates chemical or biological
degradation of
materials, which also pollute the indoor air. Dampness has
therefore been suggested to be a strong, consistent indicator for
the risk of asthma and respiratory symptoms. The health risks of
biological contaminants within the indoor environment could be
addressed by considering dampness as the risk indicator.
There
is clinical evidence that exposure to mold and other
dampness-related microbial agents increases the risks of rare
conditions, such as hypersensitivity pneumonitis, allergic
alveolitis, chronic rhinosinusitis and allergic fungal sinusitis.
While those with allergies and lowered immune systems are
particularly susceptible to biological and chemical agents in damp
indoor environments, adverse health effects have also been found in
normal populations. The increasing prevalence of asthma and
allergies in many countries increase the number of people
susceptible to the effects of dampness and mold in buildings and
homes.