The following is from the recent (July, 2009) World Health
Organization's Guidelines for Indoor Air Quality, Dampness and Mold
which confirms that mold is a health hazard and that inspection and measurements can be used to confirm indoor microbial growth (note, we bolded the bold parts):
"The conditions that contribute to the health risk were summarized as follows.
On the basis of this review, the following guidelines were formulated.
- The prevalence of indoor dampness varies widely within and
among countries, continents and climate zones. It is estimated to
affect 10–50% of indoor environments in Europe, North America,
Australia, India and Japan. In certain settings, such as river valleys
and coastal areas, the conditions of dampness are substantially more
severe than the national averages for such conditions.
- The amount of water on or in materials is the most important
trigger of the growth of microorganisms, including fungi, actinomycetes
and other bacteria.
- Microorganisms are ubiquitous. Microbes propagate rapidly wherever water is available.
The dust and dirt normally present in most indoor spaces provide
sufficient nutrients to support extensive microbial growth. While mould
can grow on all materials, selection of appropriate materials can
prevent dirt accumulation, moisture penetration and mould growth.
- Microbial growth may result in greater numbers of spores, cell
fragments, alergens, mycotoxins, endotoxins, β-glucans and volatile
organic compounds in indoor air. The causative agents of adverse health
effects have not been identified conclusively, but an excess level of any of these agents in the indoor environment is a potential health hazard.
- Microbial interactions and moisture-related physical and
chemical emissions from building materials may also play a role in
dampness-related health effects.
- Building standards and regulations with regard to comfort and
health do not sufficiently emphasize requirements for preventing and
controlling excess moisture and dampness.
- Apart from its entry during occasional events (such as water leaks,
heavy rain and flooding), most moisture enters a building in incoming
air, including that infiltrating through the building envelope or that
resulting from the occupants’ activities.
- Allowing surfaces to become cooler than the surrounding air may
result in unwanted condensation. Thermal bridges (such as metal window
frames), inadequate insulation and unplanned air pathways, or cold
water plumbing and cool parts of air-conditioning units can result in
surface temperatures below the dew point of the air and in dampness.
- Persistent dampness and microbial growth on interior
surfaces and in building structures should be avoided or minimized, as
they may lead to adverse health effects.
- Indicators of dampness and microbial growth include the presence of
condenation on surfaces or in structures, visible mould, perceived
mouldy odour and a history of water damage, leakage or penetration.
Thorough inspection and, if necessary, appropriate measurements can be used to confirm indoor moisture and microbial growth.
- As the relations between dampness, microbial exposure and health
effects cannot be quantified precisely, no quantitative health-based
guideline values or thresholds can be recommended for acceptable levels
of contamination with microorganisms. Instead, it is recommended that
dampness and mould-related problems be prevented. When they occur, they
should be remediated because they increase the risk of hazardous exposure to microbes and chemicals.
- Well-designed, well-constructed, well-maintained building envelopes
are critical to the prevention and control of excess moisture and
microbial growth, as they prevent thermal bridges and the entry of
liquid or vapour-phase water.
- Management of moisture requires proper control of temperatures and
ventilation to avoid excess humidity, condensation on surfaces and
excess moisture in materials. Ventilation should be distributed
effectively throughout spaces, and stagnant air zones should be avoided.
- Building owners are responsible for providing a healthy workplace or living environment free of excess moisture and mould,
by ensuring proper building construction and maintenance. The occupants
are responsible for managing the use of water, heating, ventilation and
appliances in a manner that does not lead to dampness and mould growth.
Local recommendations for different climatic regions should be updated
to control dampness-mediated microbial growth in buildings and to ensure desirable indoor air quality.
- Dampness and mould may be particularly prevalent in poorly
maintained housing for low-income people. Remediation of the conditions
that lead to adverse exposure should be given priority to prevent an additional contribution to poor health in populations who are already living with an increased burden of disease.
- The guidelines are intended for worldwide use, to protect public health
under various environmental, social and economic conditions, and to
support the achievement of optimal indoor air quality. They focus on
building characteristics that prevent the occurrence of adverse health effects associated with dampness or mould.
The guidelines pertain to various levels of economic development and
different climates, cover all relevant population groups and propose
feasible approaches for reducing health risks due to dampness and microbibial contamination. Both private and public buildings (e.g. offices and nursing homes) are covered, as dampness and mould are risks
everywhere. Settings in which there are particular production processes
and hospitals with high-risk patients or sources of exposure to
pathogens are not, however, considered.
- While the guidelines provide objectives for indoor air quality
management, they do not give instructions for achieving those
objectives. The necessary action and indicators depend on local
technical conditions, the level of development, human capacities and
resources. The guidelines recommended by WHO acknowledge this
heterogeneity. In formulating policy targets, governments should
consider their local circumstances and select actions that will ensure achievement of their health objectives most effectively."