Indoor Air Quality Testing
It is important to realize and understand that everyone
is exposed to mold throughout their lives. Exposures
to mold are virtually inevitable in everyday life
because mold of one kind or another is ever-present in the
indoor and outdoor environment. Thus, such exposures can
be considered “unavoidable”, “tolerable”, or
“acceptable” for the majority of healthy persons.
Mold grows throughout the natural as well as the built
environment. Tiny particles of mold are present in both
indoor and outdoor air. Mold produce microscopic cells
called “spores” which are extremely tiny and spread
easily through the air. This is how they reproduce. Mold
spores are present through the indoor and outdoor air
continually. When mold spores land on a damp spot
indoors, they may begin growing and digesting whatever
they are growing on in order to survive. There are mold
that can grow on wood, paper, carpet, and foods.
When excessive moisture or water accumulates indoors,
mold growth will often occur, particularly if the
moisture problem remains undiscovered or un-addressed.
There is no practical way to eliminate all mold and
mold spores in the indoor environment. The way to
control indoor mold growth is to control moisture.
The most critical step in solving a mold problem is to
accurately identify and rectify the moisture sources that
allowed the growth to occur. In order to prevent mold
from growing, it is imperative that water damaged areas
be dried within a 24-48 period. If mold is a problem in
the home, the mold must be cleaned up and the excess
water or moisture removed. There are many common
mold is made with respect to
their most common impact
to human health. Many genera of molds have
sources of excess moisture that can
contribute to indoor mold
growth. Some of the primary means
species with varying
characteristics. of moisture
entry into homes and
buildings are water leakage (such as roof or plumbing
leaks), vapor migration, capillary movement, air
infiltration, humidifier use, and inadequate venting of
kitchen and bath humidity. Temperature must also be
considered because of its role in moisture transfer and
condensation. The key is to reduce indoor humidity
and identify the molds’ point of origin.
Mold Testing Purposes
If the source of moisture is not easily detected, mold
testing can prove beneficial. Often a roof leak or a
plumbing leak can be identified as the source. The
difficulty arises when there is an odor present or when an
occupant shows signs of mold exposure but no visible
mold is discovered.
Scope of Remediation/Restoration:
The area that is contaminated and the extent of the
contamination will determine the scope of the remediation
required. Following the completion of the remediation
process, mold testing should be performed to obtain
Mold Sampling Methods
A wide variety of analytical methods are available to
investigators to study biological agents in indoor
environments. Since there are no generally accepted
guidelines for fungi or bacteria, comparison with
reference samples is the most useful approach. Reference
samples are usually outdoor samples and
samples from “non-complaint” areas. In general, indoor
fungal concentrations should be similar to or lower
than outdoor levels. If fungi at a significant level are
only found indoors, this often suggests indoor
amplification of the fungi. Furthermore, the detection
of some fungi, even at low levels, may require further
The word “sample” means different things in different
contexts. At times, investigators use the term to
designate an individual measurement (e.g., an air or
source sample). However, a sample may also designate
a set of measurements (e.g., multiple measurements of
some parameter that comprise a sample of size n). In
either case, the goal of sampling is to learn about
entire populations by looking at subsets of the members of
There are several types of testing methods that can
detect the presence of mold. They can be used to find
mold particles which are suspended in air, in settled
dust, or growing on surfaces of building materials and
furnishings. Some methods can identify a portion of the
types of live molds in a sampled environment.
Surface Sampling Methods
Surface sampling can be useful for differentiating
between mold growth and stains, for identifying the type of
mold growth that may be present and, in some instances,
identifying signs of mold growth in a general
vicinity. Surface sampling can improve the accuracy of
the results and interpretation of the inspected
environment if sampled correctly, although not required.
The following are the different types of surface
samples that are commonly used to perform a direct
examination of a specific location:
Tape (or tape-lift)
These samples can be collected using clear adhesive tape
or packing tape. For microscopic examination of
collected particles, adhesive tapes must be of good
optical quality and compatible with any stains the
analytical laboratory may use on the specimens. Easily
removed material is collected by touching the tape
gently to a test surface and removing the tape with a
These are portions of environmental materials (e.g.,
settled dust, sections of wall board, pieces of duct lining,
carpet segments, or return-air filters) tested to
determine if they may contain or be contaminated with
biological agents. The objective of such sampling is to
collect a portion of material small enough to be
transported conveniently and handled easily in the
laboratory while still representing the material being
sampled. Samples obtained using this method can be
analyzed using culturing or direct microscopy.
These are very similar to tape samples except for a
sterile wipe (looks like a long Q-tip) is used to test an area
of suspected mold. Samples obtained using this method
can be analyzed using culturing or direct microscopy.
Air Sampling Methods
Air samples are possibly the most common type of
environmental sample that investigators collect to study
bioaerosols. The physics of removing particles from the
air and the general principles of good sample
collection apply to all airborne materials, whether
biological or other origin. Therefore, many of the basic
principles investigators use to identify and quantify
other airborne particulate matter can be adapted to
bioaerosol sampling. Common to all aerosol samplers is
consideration of collection efficiency. The following
are the two most common forms of air sampling methods:
The Micro5 Microcell uses spore trap cassettes in
conjunction with a portable air pump to rapidly collect
airborne aerosols including mold, pollen and other
particulates. Air is drawn through a small opening at the
top of the cassette and spores are trapped on a sticky
surface inside the cassette.
These are similar to the Micro5 spore trap cassettes in
that they are also used in conjunction with portable air
pumps. The difference is in the air flow sampling rate.
The term “data” can vary and may consist of the simple
observation of fungal growth on a wall, analytical
measurements from hundreds of environmental samples, or
the results of a survey of building occupants with
and without particular building-related conditions. Data
interpretation is the process whereby investigators
make decisions on (a) the relevance to human exposure of
environmental observations and measurements,
(b) the strength of associations between exposure and
health status, and (c) the probability of current or
future risks. These interpretation steps are followed by
decisions on what measures can be taken to interrupt
exposure and prevent future problems.
Remediation of Mold
Prevention of mold growth indoors is only possible if
the factors that may allow it are identified and controlled.
When prevention has failed and visible growth has
occurred in a home or building, restoration requires (a)
removal of porous materials showing extensive microbial
growth, (b) physical removal of surface microbial
growth on non-porous materials to typical background
levels, and (c) reduction of moisture to levels that do
not support microbial growth. Identification of the
conditions that contributed to microbial proliferation in a
home or building is the most important step in
remediation. No effective control strategy can be implemented
without a clear understanding of the events or building
dynamics responsible for microbial growth.
Symptoms of Mold Exposure
The most common symptoms of mold exposure are runny
nose, eye irritation, cough, congestion, and
aggravation of asthma. Individuals with persistent
health problems that appear to be related to mold or other
types of air quality contaminant exposure should see
their physicians for a referral to specialists who are
trained in occupational/environmental medicine or
related specialties and are knowledgeable about these
types of exposures. Decisions about removing individuals
from an affected area must be based on the results
of such medical evaluation. Since mold is naturally
present in outdoor environments and we share the same
air between the indoors and the outdoors, it is
impossible to eliminate.
Mold Recap: Ten Things You Should Know About Mold
1) Potential health effects and symptoms associated with
mold exposures include allergic reactions,
asthma, and other respiratory problems.
2) There is no practical way to eliminate mold and mold
spores in the indoor environment; the way to
control indoor mold growth is to control moisture.
3) If mold is a problem in your home or building, you
must clean up the mold and eliminate sources of
4) The source of the water problem or leak must be
repaired to prevent mold growth.
5) Indoor humidity must be reduced (to 30-60%) to
decrease mold growth by: adequately venting
bathrooms, dryers, and other moisture-generating sources
to the outside; using air conditioners and dehumidifiers;
increasing ventilation; and using exhaust fans whenever
cooking, dishwashing and cleaning.
6) Clean and dry any damp or wet building materials and
furnishings within 24-48 hours to prevent mold
7) Clean mold off of hard surfaces with water and
detergent and dry completely.
8) Prevent condensation: reduce the potential for
condensation on cold surfaces (e.g., windows, piping,
exterior walls, roof, or floors) by adding insulation.
9) In areas where there is a perpetual moisture problem,
do not install carpeting.
10) Mold can be found almost anywhere; they can grow on
virtually any substance, providing moisture is
present. There are molds that can grow on wood, paper,
carpet, and foods.
Note: The only way to be sure of the presence of
mold in the home is through lab testing. We strongly
recommend lab testing for mold prior to the closing
of your home, visual inspections can not and should
not be relied upon as a definitive analysis for the
presence of mold.
Failure to perform laboratory testing for mold
relieves Florida Master Home inspectors, inc and its officers and
employees of any present or future liability. We will be glad to provide
you with a free quote for lab testing.
References & Resources
Airborne Allergens, William Solomon, Guest Editor.
Immunology & Allergy Clinics of North America,
Volume 9, Number 2, August 1989. W.B. Saunders Company,
Publishers, The Curtis Center,
Independence Square West, Philadelphia, PA
19106-3399. This book may be out of print.
Bioaerosols: Assessment and Control, Janet Macher, Sc.D.,
M.P.H., Editor. 1999. ACGIH, 1330
Kemper Meadow Drive, Cincinnati, OH 45240-1634.
Bioaerosols, Harriet Burge, Ph.D. 1995. Lewis
Publishers, 2000 Corporate Blvd., N.W., Boca
Raton, FL 33431-9868.
Biological Contaminants in Indoor Environments, Morey,
Feeley, Otten, Editors. 1990. ASTM, 1916
Race Street, Philadelphia, PA 19103. STP 1071.
Fungi and Bacteria in Indoor Air Environments: Health
Effects, Detection and Remediation,
Proceedings from the International Conference, Saratoga
Springs, NY October 6-7, 1994.
Health Implications of Fungi in Indoor Environments,
Edited by R.A. Samson. 1994. Elsevier
Science, P.O. Box 945, Madison Square Station, New York,
Indoor Air and Human Health, Gammage & Kaye. 1985. Lewis
Microfungi, S.G. Gravesen, J.C. Frisvad, & R.A. Samson,
published by Munksgaard.
American Conference of Governmental Industrial
Hygienists - information on IAQ and useful links.
American Industrial Hygiene Association - general IAQ
California Environmental Protection Agency - California
Environmental Protection Agency - information regarding
prevention and remediation of mold
New York State Department of Health - New York state
recommendations for IAQ, indoor mold
inspections, remediation, and prevention
National Institutes of Health - information regarding
environmental health issues, including IAQ
National Institute of Environmental Health Sciences -
information on mold
Remove mold for a healthy home