Investigating and Remediating Mold
in Minnesota Public Schools
This web page summarizes the main messages of the Recommended
Best Practices for Mold Investigations in Minnesota Schools and provides additional public health advice on mold in schools.
This "best practices" guidance document was created by
the Minnesota Department of Health (MDH) to assist public school
staff in investigating the causes of indoor mold concerns and in
finding cost-effective solutions. The intended audience is staff
of Minnesota public schools such as Indoor Air Quality Coordinators,
facilities and maintenance personnel, health and safety staff, and
other school officials.
If mold can be seen or smelled, it is a concern. However, every
school contains some mold. So do our homes, offices and the outdoor
air.
When live mold spores encounter moisture from building problems
such as flooding, water intrusion, an ongoing leak, or even high
relative humidity, they may be able to grow. Once mold is established,
the amount of mold may increase quickly and colonies can spread
if enough moisture is available. Moisture control is the key to
preventing and controlling mold problems.
Mold may affect people's health and comfort when it has been allowed
to grow and multiply indoors. When this happens, the chances increase
that students and staff may be exposed to high levels of mold. People
can be exposed by breathing airborne mold particles, getting mold
in their eyes, by swallowing moldy food items, or by skin contact
with moldy materials.
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Health effects of exposure to indoor mold can range from mild to
severe. However, specific health effects can be difficult to predict
for any given individual. Effects may depend on the types and amounts
of mold present and conditions under which they are present. Susceptibility
to the effects of mold also varies from person to person and may
depend on an individual's health status. Allergic responses or allergy-like
symptoms, such as irritation of eyes, nose and throat, runny nose,
and rashes, are the most commonly reported problems. Although rare,
more severe effects such as asthma attacks, hypersensitivity pneumonitis,
infections, or toxic reactions are also possible.
People most likely to be susceptible to some of the effects of
mold include those with respiratory problems such as allergies or
asthma, a compromised immune system, or the elderly and the very
young. MDH recommends that anyone who is concerned that they
may have health problems due to mold, see a medical professional
experienced in such matters.
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The Minnesota Department of Health does not recommend mold testing
during the initial efforts to respond to a potential mold problem.
Furthermore, in the department's opinion, there is no practical,
health-based reason to test any visible mold found in a school.
MDH considers any active or visible mold growth as a potential health
hazard that should be properly corrected as soon as possible.
MDH recommends that school staff rely mainly, at least initially,
on the most practical investigation methods appropriate for the
situation. The mold investigation guidance describes techniques
for identifying conditions in need of intervention, including collecting
building history and occupant observations, performing visual and
odor assessments, using appropriate moisture diagnostics and mold
testing (but only if necessary and when it can be done properly).
When it is done properly, mold testing can be a useful tool to help
find and assess areas needing correction. It can also be a valuable
part of evaluating the success of clean up efforts.
From a public health view, the goals of any mold investigation
should always be to locate sites of growth in order to determine
how best to control the underlying moisture problem and remove the
contamination. The MDH document emphasizes that school staff need
to focus on the most critical steps for correcting a mold problem;
namely, to find and fix the source(s) of excess moisture and to
locate and physically remove the contamination. If mold testing
is used as part of an investigation, MDH recommends that school
staff follow the investigation and testing advice provided in the
guidance document.
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Mold testing, as it is typically done, gives a very unreliable
"measurement" of the amount of mold present or of what
people are exposed to. All of the commonly used testing and analytical
techniques have limitations in what they can detect and quantify.
For a number of reasons, mold-testing results alone should not be
used to predict safety or to rule out potential health risks. Unfortunately,
without strong evidence of health symptoms, questions about health
and safety for occupants of a moldy building can be extremely difficult
to answer or predict.
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The term "toxic mold" is largely a creation of the popular
media. Currently, there is no complete list of molds that are harmful
to humans. In fact, it is likely that many if not all types of mold
can cause health problems for some people under certain conditions.
There has been relatively little effort to date to identify and
test the toxicity of the many different molds that exist. So, despite
current knowledge that certain organisms can cause problems for
some portion of the population, the full range of health effects
caused by most molds is not well understood at this time. For this
and other reasons, it is not appropriate to conduct testing solely
to find out if specific kinds of mold are present or to rule out
the presence of so called "toxic" molds.
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The mere detection of mold does not necessarily warrant evacuation.
It is, in fact, quite normal to find some mold in indoor environments.
Even when active mold growth is found, it is too early to conclude
that occupants are at risk or need to be removed. The decision to
move people should involve careful evaluation of a number of factors.
It is the responsibility of the school officials to determine if
evacuation or some other form of control is needed to protect occupants.
MDH suggests consideration of the following:
- What areas, if any, should be evacuated?
- What is the basis for the decision and how will it be communicated?
- Who should leave, if a full evacuation is not planned?
- What impacts will evacuation or relocation have on students
and staff?
- If people are relocated, is new location better?
- What criteria will be used to determine when to re-occupy and
how will the decision be communicated.
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It is ultimately up to the school's staff to determine what is
needed to resolve any real or perceived mold problem in their building.
Many aspects of mold investigation and clean-up decisions must rely
on professional judgment and other situation-specific factors -
including issues such as budget considerations, potential liability,
perceived nature and extent of the problem, as well as the skill
and experience of the clean-up workers.
The presence of mold growth in a school is a sign of some design,
operation, or maintenance failure or accident, such as a water pipe
breaking. A school that is handling a mold problem properly should
be able to demonstrate that the moisture problem is being investigated
and corrected and that mold contamination is being removed using
effective methods to restore the site to a clean condition.
The MDH mold investigation guidance describes basic concepts of
mold clean-up and lists additional resources on the subject. MDH
is preparing a companion document to provide further guidance on
the clean-up of school mold problems. In most cases, when small
amounts of mold growth are found, school staff should be able to
remove the mold by carefully following the practices and procedures
described. Detailed cleaning methods should be used to capture and
trap mold particles during removal from non-porous smooth surfaces.
When thorough cleaning is unlikely to succeed, removal of the contaminated
materials is advised. Considerations for protecting school occupants
and limiting the spread of contaminants are also described in the
MDH guidance. When contamination is extensive or beyond the abilities
of the school district's staff who perform routine cleaning, it
is recommended that experienced and trained workers perform mold
removal and clean-up.
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The Minnesota Department of Health has no regulatory authority
specific to mold in schools. The Indoor Air Unit will provide assistance
to school districts, if requested by school officials. Depending
on the problem, the assistance may be general information on mold
and/or technical advice regarding testing, data interpretation and
contaminant removal. MDH does not perform mold or other types of
indoor air quality testing.
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For questions about this page or indoor air quality, please contact the Indoor
Air Unit at health.indoorair@state.mn.us, 651-201-4601 or 800-798-9050.
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Factsheet: Investigating and Remediating Mold in Minnesota Public Schools (PDF: 22KB/4 pages) 
