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This World Health Organization report, published July 16, 2009, verifies that which suffering millions and The Center for School Mold Help have been reporting, which the United States Centers for Disease Control, health departments, and most US physicians have downplayed and denied - that mold and dampness cause serious health problems, including respiratory and immunological. The WHO emphasizes that mold should be avoided as a major health risk, explains how to prevent and address indoor mold, and points out that building owners have the responsibility to provide healthy indoor air. This document will begin the changes needed to rescue the world population from the devastating impact of indoor mold (mould) and dampness, especially within our schools and homes. We salute the World Health Organization for its accomplishment in producing this groundbreaking report and expect that the United States Centers for Disease Control will quickly follow with a position on mold and dampness, in step with the WHO. There is no more doubt - mold and dampness harms and can kill. We cannot tolerate this in our schools and buildings. (SMH)
"The authors conclude that occupants of damp or mouldy buildings, both private and public, have up to a 75% greater risk of respiratory symptoms and asthma. The guidelines recommend the prevention or remediation of dampness- and mould-related problems to significantly reduce harm to health...In damp conditions, hundreds of species of bacteria and fungi grow indoors and emit spores, cell fragments and chemicals into the air. Exposure to these contaminants is associated with the incidence or worsening of respiratory symptoms, allergies, asthma and immunological reactions. Children are particularly susceptible. " (WHO Press Release, 7/16/09)
READ the press release and link to full report, below.
| When sufficient moisture is available, hundreds of species of bacteria and fungi - particularly mould - pollute indoor air. The most important effects of exposure to these pollutants are the increased prevalence of respiratory symptoms, allergies and asthma, as well as disturbance of the immune system. Preventing (or minimizing) persistent dampness and microbial growth on interior surfaces and building structures is the most important means of avoiding harmful effects on health. |
This book provides a comprehensive overview of the scientific evidence on the health problems associated with this ubiquitous pollution and provides WHO guidelines to protect public health. It also describes the conditions that determine the presence of mould and provides measures to control its growth indoors." (WHO, 2009)
SMH Note: The word school is mentioned 51 times in this report, with approx. 50 studies listed related to school mold and dampness. The quote below is of concern:
" Dampness and indoor mould also occur in school buildings, day-care centres, offices and other buildings (Mudarri, Fisk, 2007). The health risks associated with dampness-related exposures in these building are likely to be similar to those in damp houses; however, no systematic surveys have been conducted to assess the prevalence of dampness and mould in these establishments." (WHO Guidelines for IAQ: Dampness and Mould, p.27)
While The Center for School Mold Help (SMH) commends the WHO on their findings, we find the report to be lacking in some areas, which is to be expected in a work in progress. However, the severity of the health impacts calls for, on an urgent basis, more comprehensive coverage.
We disagree with this statement, above, that "no systematic surveys have been conducted to assess the prevalence of dampness and mould in these establishments", as the American Federation of Teachers (AFT), the US EPA and US GAO have conducted studies and surveys that indicate the extensive pervasiveness of dampness and mold in the United States public schools - both old and new. Therefore, the WHO report does not go far enough in exploring the problem of dampness and mold in schools or in naming the dangers of school-derived health impacts of mold and dampness exposure as entire populations of countries may become sickened by cycling through dangerous, damp school buildings.
We also have had numerous comments related to this report, in less than a week. One most frequently heard is the report does not include the very serious cognitive and neurological problems often clinically found with mold-related illnesses. We encourage you to contact the WHO with your concerns and supporting research, if any, as this book is the first in a series, and the future volumes may contain more of what the public is experiencing. These WHO Guidelines for IAQ: Dampness and Mould may be of help for Worker's Compensation and legal cases involving illnesses allegedly derived from damp buildings and/or mold. Attorneys, physicians and health-care providers, professionals, school districts, teacher unions, teachers, parents, realtors, insurers, legislators, health departments, and the general public will be interested in this publication. Our site visitors could provide the electronic links for this comprehensive information, on our site, by email or order a hard copy, for these individuals in your locale, state, and on a national basis. (SMH)
Dr Michal Krzyzanowski
Regional Adviser, Noncommunicable Diseases
WHO Regional Office for Europe
Hermann-Ehlers-Straße 10 D-53113 Bonn, Germany
Tel.: +49 228 815 0400. Fax +49 228 815 0440
Ms Cristiana Salvi
Technical Officer, Partnership and Communications
WHO Regional Office for Europe
Via Francesco Crispi 10, I-00187 Rome, Italy
Tel.: +39 06 4877543; mobile: +39 348 0192305
Fax: +39 06 4877599; E-mail:
Click here: WHO/Europe - WHO publishes first indoor air quality guidelines on dampness and mould
WHO publishes first indoor air quality guidelines on dampness and mould
"Microbial pollution is a key element of indoor air pollution. It is caused by hundreds
of species of bacteria and fungi, in particular filamentous fungi (mould),
growing indoors when sufficient moisture is available. This document provides
a comprehensive review of the scientific evidence on health problems associated
with building moisture and biological agents. The review concludes that the most
important effects are increased prevalences of respiratory symptoms, allergies
and asthma as well as perturbation of the immunological system. The document
also summarizes the available information on the conditions that determine the
presence of mould and measures to control their growth indoors. WHO guidelines
for protecting public health are formulated on the basis of the review. The
most important means for avoiding adverse health effects is the prevention (or
minimization) of persistent dampness and microbial growth on interior surfaces
and in building structures." (WHO, 2009)
Click here for WHO guidelines on IAQ: Dampness and Mould: http://www.euro.who.int/document/E92645.pdf
WHO guidelines for indoor air quality : dampness and mould
World Health Organization 2009
Healthy indoor air is recognized as a basic right. People spend a large part of their
time each day indoors: in homes, offices, schools, health care facilities, or other
private or public buildings. The quality of the air they breathe in those buildings
is an important determinant of their health and well-being. The inadequate control
of indoor air quality therefore creates a considerable health burden.
Indoor air pollution – such as from dampness and mould, chemicals and other
biological agents – is a major cause of morbidity and mortality worldwide. About
1.5 million deaths each year are associated with the indoor combustion of solid
fuels, the majority of which occur among women and children in low-income
Knowledge of indoor air quality, its health significance and the factors that
cause poor quality are key to enabling action by relevant stakeholders – including
building owners, developers, users and occupants – to maintain clean indoor air.
Many of these actions are beyond the power of the individual building user and
must be taken by public authorities through the relevant regulatory measures
concerning building design, construction and materials, and through adequate
housing and occupancy policies. The criteria for what constitutes healthy indoor
air quality provided by these guidelines are therefore essential to prevent disease
related to indoor air pollution.
These guidelines were developed by the WHO Regional Office for Europe in
collaboration with WHO headquarters as part of the WHO programme on indoor
air pollution. Further guidelines on indoor air quality in relation to pollution
emanating from specific chemicals and combustion products are under
The WHO guidelines on indoor air quality: dampness and mould offer guidance
to public health and other authorities planning or formulating regulations,
action and policies to increase safety and ensure healthy conditions of buildings.
The guidelines were developed and peer reviewed by scientists from all over the
world, and the recommendations provided were informed by a rigorous review
of all currently available scientific knowledge on this subject. We at WHO thank
these experts for their efforts, and believe that this work will contribute to improving
the health of people around the world.
WHO Regional Director for Europe
X I I EXECUTIVE SUMMARY
This document presents World Health Organization (WHO) guidelines for the
protection of public health from health risks due to dampness, associated microbial
growth and contamination of indoor spaces. The guidelines are based on a
comprehensive review and evaluation of the accumulated scientific evidence by
a multidisciplinary group of experts studying health effects of indoor air pollutants
as well as those specialized in identification of the factors that contribute to
microbial growth indoors.
Problems of indoor air quality are recognized as important risk factors for human
health in both low-income and middle- and high-income countries. Indoor
air is also important because populations spend a substantial fraction of time
within buildings. In residences, day-care centres, retirement homes and other
special environments, indoor air pollution affects population groups that are particularly
vulnerable due to their health status or age. Microbial pollution involves
hundreds of species of bacteria and fungi that grow indoors when sufficient
moisture is available. Exposure to microbial contaminants is clinically associated
with respiratory symptoms, allergies, asthma and immunological reactions.
The microbial indoor air pollutants of relevance to health are widely heterogeneous,
ranging from pollen and spores of plants coming mainly from outdoors,
to bacteria, fungi, algae and some protozoa emitted outdoors or indoors. They
also include a wide variety of microbes and allergens that spread from person to
person. There is strong evidence regarding the hazards posed by several biological
agents that pollute 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 cannot be identified. This is
due to the fact that people are often exposed to multiple agents simultaneously,
to complexities in accurately estimating 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 the indoor environment is due to
dampness and inadequate ventilation. Excess moisture on almost all indoor materials
leads to growth of microbes, such as mould, fungi and bacteria, which
subsequently emit spores, cells, fragments and volatile organic compounds into
indoor air. Moreover, dampness initiates chemical or biological degradation of
materials, which also pollutes indoor air. Dampness has therefore been suggested
to be a strong, consistent indicator of risk of asthma and respiratory symptoms
(e.g. cough and wheeze). The health risks of biological contaminants of indoor
air could thus be addressed by considering dampness as the risk indicator.
X I I I
Health hazards result from a complex chain of events that link penetration
of water indoors, excessive moisture to biological growth, physical and chemical
degradation, and emission of hazardous biological and chemical agents. The review
of scientific evidence that supports these guidelines follows this sequence of
events. The issues related to building dampness and its effect on indoor exposure
to biological and non-biological pollutants are summarized in Chapter 2, which
also addresses approaches to exposure assessment. An important determinant of
dampness and biological growth in indoor spaces is ventilation, and this issue is
discussed in Chapter 3. The evidence for the health effects of indoor exposure is
presented in Chapter 4, based on a review of epidemiological studies and of clinical
and toxicological research on the health effects of dampness and mould. The
results of the epidemiological and toxicological studies are summarized in the
The background material for the review was prepared by invited experts and
discussed at a WHO working group meeting, convened in Bonn, Germany, 17–
18 October 2007. The conclusions of the working group discussion are presented
in Chapter 5 and are reproduced in this executive summary, as follows.
Sufficient epidemiological evidence is available from studies conducted in different
countries and under different climatic conditions to show that the occupants
of damp or mouldy buildings, both houses and public buildings, are at
increased risk of respiratory symptoms, respiratory infections and exacerbation
of asthma. Some evidence suggests increased risks of allergic rhinitis and
asthma. Although few intervention studies were available, their results show
that remediation of dampness can reduce adverse health outcomes.
There is clinical evidence that exposure to mould and other dampness-related
microbial agents increases the risks of rare conditions, such as hypersensitivity
pneumonitis, allergic alveolitis, chronic rhinosinusitis and allergic fungal
Toxicological evidence obtained in vivo and in vitro supports these findings,
showing the occurrence of diverse inflammatory and toxic responses after
exposure to microorganisms isolated from damp buildings, including their
spores, metabolites and components.
While groups such as atopic and allergic people are particularly susceptible to
biological and chemical agents in damp indoor environments, adverse health
effects have also been found in nonatopic populations.
The increasing prevalences of asthma and allergies in many countries increase
the number of people susceptible to the effects of dampness and mould in
X I V WHO GUIDELINES FOR INDOOR AIR QUA L I TY: DAMPNESS AND MOULD
The conditions that contribute to the health risk were summarized as follows.
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, allergens,
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’
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.
On the basis of this review, the following guidelines were formulated.
Persistent dampness and microbial growth on interior surfaces and in building
structures should be avoided or minimized, as they may lead to adverse
Indicators of dampness and microbial growth include the presence of condensation
on surfaces or in structures, visible mould, perceived mouldy odour
EXECUTIVE SUMMARY XV
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
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 microbial 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
XVI WHO GUIDELINES FOR INDOOR AIR QUA L I TY: DAMPNESS AND MOULD
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.
Executive summary xii
1. Introduction 1
1.1 Background 1
1.2 Scope of the review 3
1.3 Preparation of the guidelines 5
1.4 Guidelines and indoor air quality management 6
2. Building dampness and its effect on indoor exposure to biological
and non-biological pollutants 7
2.1 Frequency of indoor dampness 7
2.2 Effects of dampness on the quality of the indoor environment 9
2.3 Dampness-related indoor pollutants 13
2.4 Exposure assessment 20
2.5 Summary and conclusions 29
3. Moisture control and ventilation 31
3.1 Introduction 31
3.2 Sources of moisture 34
3.3 Mould and mites as indicators of building performance 37
3.4 Ventilation performance 41
3.5 Ventilation systems 42
3.6 Outdoor and other sources of pollution related to ventilation 49
3.7 Ventilation and spread of contaminants 51
3.8 Moisture control in buildings 55
3.9 Measures to protect against damage due to moisture 58
3.10 Conclusions and recommendations 61
4. Health effects associated with dampness and mould 63
4.1 Review of epidemiological evidence 63
4.2 Clinical aspects of health effects 78
4.3 Toxicological mechanisms 84
4.4 Synthesis of available evidence on health effects 89
5. Evaluation of human health risks and guidelines 93
5.1 Summary 93
5.2 Conditions that contribute to health risks 93
5.3 Guidelines 94
6. References 97
Annex 1. Summary of epidemiological studies 133
Annex 2. Summary of in vitro and in vivo studies 215
Development of WHO Guidelines for Indoor Air Quality: Dampness and Mold
World Health Organization
Development of WHO Guidelines for Indoor Air Quality: Dampness and Mold
Report of a Working Group on Mold (published 2008)
This very significant document provides an overview of the known risks from mold exposure, and what should be done
about them (recommendations). As a primarily European workgroup, it is interesting to note the difference in what the
U.S. Centers for Disease Control is telling us about mold and health and what this workgroup from the esteemed World
Health Organization found to be true. At The Center for School Mold Help, we find this document as an accurate
beginning in describing the problem of mold on health, as experienced in damp buildings - and in the case of the United
States, this describes most schools (SMH).
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